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Square array of binomial coefficients T(n,k) = binomial(n,k), n >= 0, k >= 0, read by downward antidiagonals.
+10
36
1, 0, 1, 0, 1, 1, 0, 0, 2, 1, 0, 0, 1, 3, 1, 0, 0, 0, 3, 4, 1, 0, 0, 0, 1, 6, 5, 1, 0, 0, 0, 0, 4, 10, 6, 1, 0, 0, 0, 0, 1, 10, 15, 7, 1, 0, 0, 0, 0, 0, 5, 20, 21, 8, 1, 0, 0, 0, 0, 0, 1, 15, 35, 28, 9, 1, 0, 0, 0, 0, 0, 0, 6, 35, 56, 36, 10, 1, 0, 0, 0, 0, 0, 0, 1, 21, 70, 84, 45, 11, 1, 0, 0, 0, 0
OFFSET
0,9
COMMENTS
The signed triangular matrix T(n,k)*(-1)^(n-k) is the inverse matrix of the triangular Catalan convolution matrix A106566(n,k), n=k>=0, with A106566(n,k) = 0 if n<k. - Philippe Deléham, Aug 01 2005
As a number triangle: unsigned version of A109466. - Philippe Deléham, Oct 26 2008
A063967*A130595 as infinite lower triangular matrices. - Philippe Deléham, Dec 11 2008
Modulo 2, this sequence becomes A106344. - Philippe Deléham, Dec 18 2008
Let {a_(k,i)}, k>=1, i=0,...,k, be the k-th antidiagonal of the array. Then s_k(n) = Sum_{i=0..k}a_(k,i)* binomial(n,k) is the n-th element of the k-th column of A111808. For example, s_1(n) = binomial(n,1) = n is the first column of A111808 for n>1, s_2(n) = binomial(n,1) + binomial(n,2) is the second column of A111808 for n>1, etc. Therefore, in cases k=3,4,5,6,7,8, s_k(n) is A005581(n), A005712(n), A000574(n), A005714(n), A005715(n), A005716(n), respectively. Besides, s_k(n+5) = A064054(n). - Vladimir Shevelev and Peter J. C. Moses, Jun 22 2012
As a triangle, T(n,k) = binomial(k,n-k). - Peter Bala, Nov 27 2015
For all n >= 0, k >= 0, the k-th homology group of the n-torus H_k(T^n) is the free abelian group of rank T(n,k) = binomial(n,k). See the Math Stack Exchange link below. - Jianing Song, Mar 13 2023
LINKS
Lili Mu and Sai-nan Zheng, On the Total Positivity of Delannoy-Like Triangles, Journal of Integer Sequences, Vol. 20 (2017), Article 17.1.6.
L. W. Shapiro, S. Getu, Wen-Jin Woan and L. C. Woodson, The Riordan Group, Discrete Appl. Maths. 34 (1991) 229-239.
FORMULA
As a number triangle, this is defined by T(n,0) = 0^n, T(0,k) = 0^k, T(n,k) = T(n-1,k-1) + Sum_{j, j>=0} = (-1)^j*T(n-1,k+j)*A000108(j) for n>0 and k>0. - Philippe Deléham, Nov 07 2005
As a triangle read by rows, it is [0, 1, -1, 0, 0, 0, 0, 0, 0, ...] DELTA [1, 0, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938. - Philippe Deléham, Nov 22 2006
As a number triangle, this is defined by T(n, k) = Sum_{i=0..n} (-1)^(n+i)binomial(n, i)binomial(i+k, i-k) and is the Riordan array ( 1, x*(1+x) ). The row sums of this triangle are F(n+1). - Paul Barry, Jun 21 2004
Sum_{k=0..n}x^k*T(n,k) = A000007(n), A000045(n+1), A002605(n), A030195(n+1), A057087(n), A057088(n), A057089(n), A057090(n), A057091(n), A057092(n), A057093(n) for n=0,1,2,3,4,5,6,7,8,9,10. - Philippe Deléham, Oct 16 2006
T(n,k) = A109466(n,k)*(-1)^(n-k). - Philippe Deléham, Dec 11 2008
G.f. for the triangular interpretation: -1/(-1+x*y+x^2*y). - R. J. Mathar, Aug 11 2015
For T(0,0) = 0, the triangle below has the o.g.f. G(x,t) = [t*x(1+x)]/[1-t*x(1+x)]. See A109466 for a signed version and inverse, A030528 for reverse and A102426 for a shifted version. - Tom Copeland, Jan 19 2016
EXAMPLE
Array begins
1 0 0 0 0 0 ...
1 1 0 0 0 0 ...
1 2 1 0 0 0 ...
1 3 3 1 0 0 ...
1 4 6 4 1 0 ...
As a triangle, this begins
1
0 1
0 1 1
0 0 2 1
0 0 1 3 1
0 0 0 3 4 1
0 0 0 1 6 5 1
...
Production array is
0 1
0 1 1
0 -1 1 1
0 2 -1 1 1
0 -5 2 -1 1 1
0 14 -5 2 -1 1 1
0 -42 14 -5 2 -1 1 1
0 132 -42 14 -5 2 -1 1 1
0 -429 132 -42 14 -5 2 -1 1 1
... (Cf. A000108)
MAPLE
seq(seq(binomial(k, n-k), k=0..n), n=0..12); # Peter Luschny, May 31 2014
MATHEMATICA
Table[Binomial[k, n - k], {n, 0, 12}, {k, 0, n}] // Flatten (* Michael De Vlieger, Nov 28 2015 *)
PROG
(Magma) /* As triangle: */ [[Binomial(k, n-k): k in [0..n]]: n in [0.. 15]]; // Vincenzo Librandi, Nov 29 2015
(GAP) nmax:=15;; T:=List([0..nmax], n->List([0..nmax], k->Binomial(n, k)));;
b:=List([2..nmax], n->OrderedPartitions(n, 2));;
a:=Flat(List([1..Length(b)], i->List([1..Length(b[i])], j->T[b[i][j][1]][b[i][j][2]]))); # Muniru A Asiru, Jul 17 2018
CROSSREFS
The official entry for Pascal's triangle is A007318. See also A052553 (the same array read by upward antidiagonals).
Cf. A030528 (subtriangle for 1<=k<=n).
KEYWORD
nonn,tabl,easy
AUTHOR
N. J. A. Sloane, Jan 19 2003
STATUS
approved
Coefficient of x^4 in expansion of (1+x+x^2)^n.
(Formerly M4129)
+10
30
1, 6, 19, 45, 90, 161, 266, 414, 615, 880, 1221, 1651, 2184, 2835, 3620, 4556, 5661, 6954, 8455, 10185, 12166, 14421, 16974, 19850, 23075, 26676, 30681, 35119, 40020, 45415, 51336, 57816, 64889, 72590, 80955, 90021, 99826, 110409, 121810, 134070
OFFSET
2,2
COMMENTS
a(n) = A111808(n,4) for n>3. - Reinhard Zumkeller, Aug 17 2005
If a 2-set Y and 2-set Z, having one element in common, are subsets of an n-set X then a(n-3) is the number of 5-subsets of X intersecting both Y and Z. - Milan Janjic, Oct 03 2007
Antidiagonal sums of the convolution array A213781. [Clark Kimberling, Jun 22 2012]
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 78.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Armen G. Bagdasaryan and Ovidiu Bagdasar, On some results concerning generalized arithmetic triangles, Electronic Notes in Discrete Mathematics (2018) Vol. 67, 71-77.
Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992
Eric Weisstein's World of Mathematics, Trinomial Coefficient
FORMULA
G.f.: (x^2)*(1+x-x^2)/(1-x)^5.
a(n) = binomial(n+2,n-2) + binomial(n+1,n-2) - binomial(n,n-2). - Zerinvary Lajos, May 16 2006
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5). Vincenzo Librandi, Jun 16 2012
a(n) = binomial(n,2) + 3*binomial(n,3) + binomial(n,4) (see our comment in A026729). - Vladimir Shevelev and Peter J. C. Moses, Jun 22 2012
a(n) = GegenbauerC(N, -n, -1/2) where N = 4 if 4<n else 2*n-4. - Peter Luschny, May 10 2016
E.g.f.: exp(x)*x^2*(12 + 12*x + x^2)/24. - Stefano Spezia, Jul 09 2023
MAPLE
seq(binomial(n+2, n-2) + binomial(n+1, n-2) - binomial(n, n-2), n=2..50); # Zerinvary Lajos, May 16 2006
A005712:=(-1-z+z**2)/(z-1)**5; # Conjectured (correctly) by Simon Plouffe in his 1992 dissertation.
A005712 := n -> GegenbauerC(`if`(4<n, 4, 2*n-4), -n, -1/2):
seq(simplify(A005712(n)), n=2..20); # Peter Luschny, May 10 2016
MATHEMATICA
CoefficientList[Series[(1+x-x^2)/(1-x)^5, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 16 2012 *)
LinearRecurrence[{5, -10, 10, -5, 1}, {1, 6, 19, 45, 90}, 40] (* Harvey P. Dale, Apr 30 2015 *)
PROG
(Magma) I:=[1, 6, 19, 45, 90]; [n le 5 select I[n] else 5*Self(n-1)-10*Self(n-2)+10*Self(n-3)-5*Self(n-4)+Self(n-5): n in [1..40]]; Vincenzo Librandi, Jun 16 2012
(PARI) Vec((x^2)*(1+x-x^2)/(1-x)^5+O(x^99)) \\ Charles R Greathouse IV, Sep 23 2012
CROSSREFS
a(n)= A027907(n, 4), n >= 2 (fifth column of trinomial coefficients).
KEYWORD
nonn,easy
EXTENSIONS
More terms from Vladeta Jovovic, Oct 02 2000
STATUS
approved
Left half of trinomial triangle (A027907), triangle read by rows.
+10
30
1, 1, 1, 1, 2, 3, 1, 3, 6, 7, 1, 4, 10, 16, 19, 1, 5, 15, 30, 45, 51, 1, 6, 21, 50, 90, 126, 141, 1, 7, 28, 77, 161, 266, 357, 393, 1, 8, 36, 112, 266, 504, 784, 1016, 1107, 1, 9, 45, 156, 414, 882, 1554, 2304, 2907, 3139, 1, 10, 55, 210, 615, 1452, 2850, 4740, 6765, 8350
OFFSET
1,5
COMMENTS
Consider a doubly infinite chessboard with squares labeled (n,k), ranks or rows n in Z, files or columns k in Z (Z denotes ...,-2,-1,0,1,2,... ); number of king-paths of length n from (0,0) to (n,k), 0 <= k <= n, is T(n,n-k). - Harrie Grondijs, May 27 2005. Cf. A026300, A114929, A114972.
Triangle of numbers C^(2)(n-1,k), n>=1, of combinations with repetitions from elements {1,2,...,n} over k, such that every element i, i=1,...,n, appears in a k-combination either 0 or 1 or 2 times (cf. also A213742-A213745). - Vladimir Shevelev and Peter J. C. Moses, Jun 19 2012
REFERENCES
Harrie Grondijs, Neverending Quest of Type C, Volume B - the endgame study-as-struggle.
LINKS
Eric Weisstein's World of Mathematics, Trinomial Triangle
Eric Weisstein's World of Mathematics, Trinomial Coefficient
FORMULA
(1 + x + x^2)^n = Sum(T(n,k)*x^k: 0<=k<=n) + Sum(T(n,k)*x^(2*n-k): 0<=k<n);
T(n, k) = A027907(n, k) = Sum_{i=0,..,(k/2)} binomial(n, n-k+2*i) * binomial(n-k+2*i, i), 0<=k<=n.
T(n, k) = GegenbauerC(k, -n, -1/2). - Peter Luschny, May 09 2016
MAPLE
T := (n, k) -> simplify(GegenbauerC(k, -n, -1/2)):
for n from 0 to 9 do seq(T(n, k), k=0..n) od; # Peter Luschny, May 09 2016
MATHEMATICA
Table[GegenbauerC[k, -n, -1/2], {n, 0, 10}, {k, 0, n}] // Flatten (* G. C. Greubel, Feb 28 2017 *)
CROSSREFS
Row sums give A027914; central terms give A027908;
T(n, 0) = 0;
T(n, 1) = n for n>1;
T(n, 2) = A000217(n) for n>1;
T(n, 3) = A005581(n) for n>2;
T(n, 4) = A005712(n) for n>3;
T(n, 5) = A000574(n) for n>4;
T(n, 6) = A005714(n) for n>5;
T(n, 7) = A005715(n) for n>6;
T(n, 8) = A005716(n) for n>7;
T(n, 9) = A064054(n-5) for n>8;
T(n, n-5) = A098470(n) for n>4;
T(n, n-4) = A014533(n-3) for n>3;
T(n, n-3) = A014532(n-2) for n>2;
T(n, n-2) = A014531(n-1) for n>1;
T(n, n-1) = A005717(n) for n>0;
T(n, n) = central terms of A027907 = A002426(n).
KEYWORD
nonn,tabl
AUTHOR
Reinhard Zumkeller, Aug 17 2005
EXTENSIONS
Corrected and edited by Johannes W. Meijer, Oct 05 2010
STATUS
approved
Coefficient of x^5 in expansion of (1 + x + x^2)^n.
(Formerly M3011 N1219)
+10
12
3, 16, 51, 126, 266, 504, 882, 1452, 2277, 3432, 5005, 7098, 9828, 13328, 17748, 23256, 30039, 38304, 48279, 60214, 74382, 91080, 110630, 133380, 159705, 190008, 224721, 264306, 309256, 360096, 417384, 481712, 553707, 634032, 723387, 822510
OFFSET
3,1
COMMENTS
If Y is a 3-subset of an n-set X then, for n>=7, a(n-4) is the number of 5-subsets of X having at most one element in common with Y. - Milan Janjic, Nov 23 2007
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 78.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
L. Carlitz et al., Permutations and sequences with repetitions by number of increases, J. Combin. Theory, 1 (1966), 350-374.
Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992
Eric Weisstein's World of Mathematics, Trinomial Coefficient
FORMULA
G.f.: x^3*(3-2*x)/(1-x)^6.
a(n) = 3*binomial(n+2,5) - 2*binomial(n+1,5).
a(n) = A111808(n,5) for n>4. - Reinhard Zumkeller, Aug 17 2005
a(n) = binomial(n+1, 4)*(n+12)/5 = 3*b(n-3)-2*b(n-4), with b(n)=binomial(n+5, 5); cf. A000389.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6). - Vincenzo Librandi, Jun 10 2012
a(n) = 3*binomial(n, 3) + 4*binomial(n, 4) + binomial(n, 5). - Vladimir Shevelev and Peter J. C. Moses, Jun 22 2012
a(n) = GegenbauerC(N, -n, -1/2) where N = 5 if 5<n else 2*n-5. - Peter Luschny, May 10 2016
a(n) = Sum_{i=1..n-1} A000217(i)*A055998(n-1-i). - Bruno Berselli, Mar 05 2018
E.g.f.: exp(x)*x^3*(60 + 20*x + x^2)/120. - Stefano Spezia, Jul 09 2023
MAPLE
A000574:=-(-3+2*z)/(z-1)**6; # conjectured by Simon Plouffe in his 1992 dissertation
seq(3*binomial(n+2, 5)-2*binomial(n+1, 5), n=3..100); # Robert Israel, Aug 04 2015
A000574 := n -> GegenbauerC(`if`(5<n, 5, 2*n-5), -n, -1/2):
seq(simplify(A000574(n)), n=3..20); # Peter Luschny, May 10 2016
MATHEMATICA
CoefficientList[Series[(3-2*x)/(1-x)^6, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 10 2012 *)
PROG
(Magma) [3*Binomial(n+2, 5)-2*Binomial(n+1, 5): n in [3..50]]; // Vincenzo Librandi, Jun 10 2012
(PARI) x='x+O('x^50); Vec(x^3*(3-2*x)/(1-x)^6) \\ G. C. Greubel, Nov 22 2017
CROSSREFS
Column m=5 of (1, 3) Pascal triangle A095660.
KEYWORD
nonn,easy
EXTENSIONS
More terms from Vladeta Jovovic, Oct 02 2000
STATUS
approved
Coefficient of x^6 in expansion of (1+x+x^2)^n.
(Formerly M4704)
+10
9
1, 10, 45, 141, 357, 784, 1554, 2850, 4917, 8074, 12727, 19383, 28665, 41328, 58276, 80580, 109497, 146490, 193249, 251713, 324093, 412896, 520950, 651430, 807885, 994266, 1214955, 1474795, 1779121, 2133792, 2545224, 3020424, 3567025, 4193322, 4908309, 5721717
OFFSET
3,2
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 78.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992
Eric Weisstein's World of Mathematics, Trinomial Coefficient
FORMULA
a(n) = binomial(n, 3)*(n^3+18*n^2+17*n-120) /120.
G.f.: (x^3)*(1+3*x-4*x^2+x^3)/(1-x)^7. (Numerator polynomial is N3(6, x) from A063420).
a(n) = A027907(n, 6), n >= 3 (seventh column of trinomial coefficients).
a(n) = A111808(n,6) for n>5. - Reinhard Zumkeller, Aug 17 2005
a(n) = 7*a(n-1) -21*a(n-2) +35*a(n-3) -35*a(n-4) +21*a(n-5) -7*a(n-6) +a(n-7). Vincenzo Librandi, Jun 16 2012
a(n) = binomial(n,3) + 6*binomial(n,4) + 5*binomial(n,5) + binomial(n,6) (see our comment in A026729). - Vladimir Shevelev and Peter J. C. Moses, Jun 22 2012
a(n) = GegenbauerC(N, -n, -1/2) where N = 6 if 6<n else 2*n-6. - Peter Luschny, May 10 2016
E.g.f.: exp(x)*x^3*(120 + 180*x + 30*x^2 + x^3)/720. - Stefano Spezia, Mar 28 2023
MAPLE
A005714:=-(1+3*z-4*z**2+z**3)/(z-1)**7; # Conjectured by Simon Plouffe in his 1992 dissertation.
A005714 := n -> GegenbauerC(`if`(6<n, 6, 2*n-6), -n, -1/2):
seq(simplify(A005714(n)), n=3..20); # Peter Luschny, May 10 2016
MATHEMATICA
a[n_] := Coefficient[(1 + x + x^2)^n, x, 6]; Table[a[n], {n, 3, 35}]
CoefficientList[Series[(1+3*x-4*x^2+x^3)/(1-x)^7, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 16 2012 *)
PROG
(Magma) I:=[1, 10, 45, 141, 357, 784, 1554]; [n le 7 select I[n] else 7*Self(n-1)-21*Self(n-2)+35*Self(n-3)-35*Self(n-4)+21*Self(n-5)-7*Self(n-6)+Self(n-7): n in [1..40]]; // Vincenzo Librandi, Jun 16 2012
(Magma) /* By definition: */ P<x>:=PolynomialRing(Integers()); [ Coefficients((1+x+x^2)^n)[7]: n in [3..35] ]; // Bruno Berselli, Jun 17 2012
KEYWORD
nonn,easy
EXTENSIONS
More terms from Vladeta Jovovic, Oct 02 2000
STATUS
approved
Triangle T(n,k) = number of k-part order-consecutive partitions of n (1<=k<=n).
+10
9
1, 1, 1, 1, 3, 1, 1, 6, 6, 1, 1, 10, 19, 10, 1, 1, 15, 45, 45, 15, 1, 1, 21, 90, 141, 90, 21, 1, 1, 28, 161, 357, 357, 161, 28, 1, 1, 36, 266, 784, 1107, 784, 266, 36, 1, 1, 45, 414, 1554, 2907, 2907, 1554, 414, 45, 1, 1, 55, 615, 2850, 6765, 8953, 6765, 2850, 615, 55
OFFSET
1,5
COMMENTS
Forms the even-indexed trinomial coefficients (A027907). Matrix inverse is A104027. - Paul D. Hanna, Feb 26 2005
Subtriangle (for 1<=k<=n) of triangle defined by [0, 1, 0, 1, 0, 0, 0, 0, 0, ...] DELTA [1, 0, 1, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938. - Philippe Deléham, Oct 29 2006
LINKS
Jean-Luc Baril, Pamela E. Harris, and José L. Ramírez, Flattened Catalan Words, arXiv:2405.05357 [math.CO], 2024. See p. 6.
Paul Barry, Jacobsthal Decompositions of Pascal's Triangle, Ternary Trees, and Alternating Sign Matrices, Journal of Integer Sequences, 19, 2016, #16.3.5.
Karl Dilcher and Larry Ericksen, Polynomials and algebraic curves related to certain binary and b-ary overpartitions, arXiv:2405.12024 [math.CO], 2024. See p. 7.
F. K. Hwang and C. L. Mallows, Enumerating nested and consecutive partitions, J. Combin. Theory Ser. A 70 (1995), no. 2, 323-333.
FORMULA
T(n, k) = Sum_{j=0..k-1} C(n-1, 2k-j-2)*C(2k-j-2, j).
G.f.: A(x, y) = (1 - x*(1+y))/(1 - 2*x*(1+y) + x^2*(1+y+y^2)) (offset=0). - Paul D. Hanna, Feb 26 2005
Sum_{k, 1<=k<=n}T(n,k)=A124302(n). Sum_{k, 1<=k<=n}(-1)^(n-k)*T(n,k)=A117569(n). - Philippe Deléham, Oct 29 2006
From Paul Barry, Sep 28 2010: (Start)
G.f.: 1/(1-x-xy-x^2y/(1-x-xy)).
E.g.f.: exp((1+y)x)*cosh(sqrt(y)*x).
T(n,k) = Sum_{j=0..n} C(n,j)*C(n-j,2*(k-j)). (End)
T(n,k) = 2*T(n-1,k) + 2*T(n-1,k-1) - T(n-2,k) - T(n-2,k-1) - T(n-2,k-2), T(1,1) = T(2,1) = T(2,2) = 1, T(n,k) = 0 if k<1 or if k>n. - Philippe Deléham, Mar 27 2014
EXAMPLE
Triangle begins:
1;
1,1;
1,3,1;
1,6,6,1;
1,10,19,10,1;
...
Triangle (0, 1, 0, 1, 0, 0, 0...) DELTA (1, 0, 1, 0, 0, 0, ...) begins:
1;
0, 1;
0, 1, 1;
0, 1, 3, 1;
0, 1, 6, 6, 1;
0, 1, 10, 19, 10, 1;
0, 1, 15, 45, 45, 15, 1;
0, 1, 21, 90, 141, 90, 21, 1;
... - Philippe Deléham, Mar 27 2014
MATHEMATICA
t[n_, k_] := Sum[ Binomial[n, j]*Binomial[n-j, 2*(k-j)], {j, 0, n}]; Flatten[ Table[t[n, k], {n, 0, 10}, {k, 0, n}]] (* Jean-François Alcover, Oct 11 2011, after Paul Barry *)
PROG
(PARI) T(n, k)=if(n<k || k<1, 0, polcoeff((1+x+x^2)^(n-1)+O(x^(2*k)), 2*k-2)) \\ Paul D. Hanna
CROSSREFS
KEYWORD
nonn,tabl,easy,nice
AUTHOR
Colin Mallows, Aug 23 2000
EXTENSIONS
More terms from James A. Sellers, Aug 25 2000
More terms from Paul D. Hanna, Feb 26 2005
STATUS
approved
T(n,k)=Number of nXk 0..2 arrays with rows and columns in lexicographic nondecreasing order but with exactly two mistakes.
+10
7
0, 0, 0, 1, 20, 1, 15, 264, 264, 15, 90, 2550, 9354, 2550, 90, 357, 22267, 201539, 201539, 22267, 357, 1107, 166762, 3576730, 11454780, 3576730, 166762, 1107, 2907, 1046418, 58069125, 514122657, 514122657, 58069125, 1046418, 2907, 6765, 5586207
OFFSET
1,5
COMMENTS
Table starts
.....0.........0.............1................15....................90
.....0........20...........264..............2550.................22267
.....1.......264..........9354............201539...............3576730
....15......2550........201539..........11454780.............514122657
....90.....22267.......3576730.........514122657...........62922179364
...357....166762......58069125.......20086951472.........6584300364020
..1107...1046418.....859516239......724313811311.......615691843257769
..2907...5586207...11336482734....24378309172117.....53477639726024161
..6765..25997719..132278417831...757386980723842...4387410446730955493
.14355.107862842.1373129978107.21490393664858691.339567886171232998387
LINKS
FORMULA
Empirical for column k:
k=1: [polynomial of degree 8]
k=2: [polynomial of degree 26]
k=3: [polynomial of degree 80]
EXAMPLE
Some solutions for n=3 k=4
..1..0..1..2. .0..0..0..0. .0..1..2..0. .0..1..1..2. .1..2..1..2
..0..0..0..2. .1..1..0..1. .0..0..0..1. .0..1..0..2. .0..2..1..0
..2..2..2..1. .0..2..1..1. .2..2..0..1. .2..0..0..2. .0..2..1..1
CROSSREFS
Column 1 is A005716(n+1).
KEYWORD
nonn,tabl
AUTHOR
R. H. Hardin, Nov 21 2016
STATUS
approved
T(n,k)=Number of nXk 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.
+10
7
0, 0, 0, 1, 13, 1, 15, 285, 285, 15, 90, 3354, 10824, 3354, 90, 357, 27521, 234484, 234484, 27521, 357, 1107, 175881, 3739008, 10776210, 3739008, 175881, 1107, 2907, 932205, 48592635, 387551595, 387551595, 48592635, 932205, 2907, 6765, 4266912
OFFSET
1,5
COMMENTS
Table starts
....0.......0..........1............15................90..................357
....0......13........285..........3354.............27521...............175881
....1.....285......10824........234484...........3739008.............48592635
...15....3354.....234484......10776210.........387551595..........11719632199
...90...27521....3739008.....387551595.......33967584488........2593097277036
..357..175881...48592635...11719632199.....2593097277036......521528860552802
.1107..932205..541463431..309971214338...175644502146694....94782697883923436
.2907.4266912.5325263364.7350438329498.10734760074025367.15624069731088285787
LINKS
FORMULA
Empirical for column k:
k=1: [polynomial of degree 8]
k=2: [polynomial of degree 24]
k=3: [polynomial of degree 70]
EXAMPLE
Some solutions for n=3 k=4
..0..1..2..1. .0..2..1..0. .0..1..2..2. .1..0..0..1. .0..2..0..2
..1..0..0..0. .2..2..2..1. .1..0..2..2. .0..2..1..0. .2..0..0..0
..2..1..0..0. .2..0..1..2. .1..2..1..0. .2..2..2..2. .2..2..2..1
CROSSREFS
Column 1 is A005716(n+1).
KEYWORD
nonn,tabl
AUTHOR
R. H. Hardin, Nov 24 2016
STATUS
approved
Coefficient of x^7 in expansion of (1+x+x^2)^n.
(Formerly M3632)
+10
6
4, 30, 126, 393, 1016, 2304, 4740, 9042, 16236, 27742, 45474, 71955, 110448, 165104, 241128, 344964, 484500, 669294, 910822, 1222749, 1621224, 2125200, 2756780, 3541590, 4509180, 5693454, 7133130, 8872231, 10960608, 13454496
OFFSET
4,1
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 78.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992
Eric Weisstein's World of Mathematics, Trinomial Coefficient
FORMULA
a(n) = binomial(n, 4)*(n^3+27*n^2+116*n-120)/210, n >= 4.
G.f.: (x^4)*(x-2)*(x^2-2)/(1-x)^8. (Numerator polynomial is N3(7, x) from A063420).
a(n) = A027907(n, 7), n >= 4 (eighth column of trinomial coefficients).
a(n) = A111808(n,7) for n>6. - Reinhard Zumkeller, Aug 17 2005
a(n) = 8*a(n-1) -28*a(n-2) +56*a(n-3) -70*a(n-4) +56*a(n-5) -28*a(n-6) +8*a(n-7) -a(n-8). Vincenzo Librandi, Jun 16 2012
a(n) = 4*binomial(n,4) + 10*binomial(n,5) + 6*binomial(n,6) + binomial(n,7) (see our comment in A026729). - Vladimir Shevelev and Peter J. C. Moses, Jun 22 2012
a(n) = GegenbauerC(N, -n, -1/2) where N = 7 if 7<n else 2*n-7. - Peter Luschny, May 10 2016
MAPLE
A005715:=(z-2)*(z**2-2)/(z-1)**8; # Conjectured by Simon Plouffe in his 1992 dissertation.
A005715 := n -> GegenbauerC(`if`(7<n, 7, 2*n-7), -n, -1/2):
seq(simplify(A005715(n)), n=4..20); # Peter Luschny, May 10 2016
MATHEMATICA
CoefficientList[Series[(x-2)*(x^2-2)/(1-x)^8, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 16 2012 *)
PROG
(Magma) I:=[4, 30, 126, 393, 1016, 2304, 4740, 9042]; [n le 8 select I[n] else 8*Self(n-1)-28*Self(n-2)+56*Self(n-3)-70*Self(n-4)+56*Self(n-5)-28*Self(n-6)+8*Self(n-7)-Self(n-8): n in [1..40]]; // Vincenzo Librandi, Jun 16 2012
(Magma) /* By definition: */ P<x>:=PolynomialRing(Integers()); [ Coefficients((1+x+x^2)^n)[8]: n in [4..33] ]; // Bruno Berselli, Jun 17 2012
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Vladeta Jovovic, Oct 02 2000
STATUS
approved
Tenth column of trinomial coefficients.
+10
3
5, 50, 266, 1016, 3139, 8350, 19855, 43252, 87802, 168168, 306735, 536640, 905658, 1481108, 2355962, 3656360, 5550755, 8260934, 12075184, 17363896, 24597925, 34370050, 47419905, 64662780, 87222720, 116470380, 154066125, 202008896, 262691396, 338962184
OFFSET
0,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (10,-45,120,-210,252,-210,120,-45,10,-1).
FORMULA
a(n) = A027907(n+5, 9).
a(n) = binomial(n+5, 5)*(n^4+66*n^3+1307*n^2+8706*n+15120) /(9!/5!).
G.f.: (1+x-x^2)*(5-5*x+x^2)/(1-x)^10, numerator polynomial is N3(9, x)= 5+0*x-9*x^2+6*x^3-x^4 from array A063420.
a(n) = A111808(n+5,9) for n>3. - Reinhard Zumkeller, Aug 17 2005
a(n) = 5*binomial(n+5,5) + 20*binomial(n+5,6) + 21*binomial(n+5,7) + 8*binomial(n+5,8) + binomial(n+5,9) (see our comment in A026729). - Vladimir Shevelev and Peter J. C. Moses, Jun 22 2012
a(n) = GegenbauerC(N, -n, -1/2) where N = 9 if 9<n else 2*n-9. - Peter Luschny, May 10 2016
MAPLE
A064054 := n -> GegenbauerC(`if`(9<n, 9, 2*n-9), -n, -1/2):
seq(simplify(A064054(n)), n=5..20); # Peter Luschny, May 10 2016
MATHEMATICA
Table[GegenbauerC[9, -n, -1/2], {n, 5, 50}] (* G. C. Greubel, Feb 28 2017 *)
PROG
(PARI) for(n=0, 25, print1(binomial(n+5, 5)*(n^4 + 66*n^3 + 1307*n^2 + 8706*n + 15120) /(9!/5!), ", ")) \\ G. C. Greubel, Feb 28 2017
CROSSREFS
A005716 (ninth column), A111808.
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Aug 29 2001
STATUS
approved

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