Search: a026672 -id:a026672
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A236830
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Riordan array (1/(1-x*C(x)^3), x*C(x)), C(x) the g.f. of A000108.
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+10
12
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1, 1, 1, 4, 2, 1, 16, 7, 3, 1, 65, 27, 11, 4, 1, 267, 108, 43, 16, 5, 1, 1105, 440, 173, 65, 22, 6, 1, 4597, 1812, 707, 267, 94, 29, 7, 1, 19196, 7514, 2917, 1105, 398, 131, 37, 8, 1, 80380, 31307, 12111, 4597, 1680, 575, 177, 46, 9, 1, 337284, 130883, 50503, 19196, 7085, 2488, 808, 233, 56, 10, 1
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OFFSET
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0,4
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COMMENTS
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LINKS
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FORMULA
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T(n,k) = Sum_{i = 0..n-k} Fibonacci(2*i-1)*binomial(2*n-2-k-i,n-k-i).
The n-th row polynomial of row reverse triangle is the n-th degree Taylor polynomial of the rational function (1 - 3*x + 2*x^2)/(1 - 3*x + x^2) * 1/(1 - x)^n about 0. For example, for n = 4, (1 - 3*x + 2*x^2)/(1 - 3*x + x^2) * 1/(1 - x)^4 = 1 + 4*x + 11*x^2 + 27*x^3 + 65*x^4 + O(x^5), giving row 4 as (65, 27, 11, 4, 1). (End)
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EXAMPLE
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Triangle begins:
1;
1, 1;
4, 2, 1;
16, 7, 3, 1;
65, 27, 11, 4, 1;
267, 108, 43, 16, 5, 1;
1105, 440, 173, 65, 22, 6, 1;
4597, 1812, 707, 267, 94, 29, 7, 1;
19196, 7514, 2917, 1105, 398, 131, 37, 8, 1;
Production matrix is:
1 1
3 1 1
6 1 1 1
10 1 1 1 1
15 1 1 1 1 1
21 1 1 1 1 1 1
28 1 1 1 1 1 1 1
36 1 1 1 1 1 1 1 1
45 1 1 1 1 1 1 1 1 1
55 1 1 1 1 1 1 1 1 1 1
66 1 1 1 1 1 1 1 1 1 1 1
78 1 1 1 1 1 1 1 1 1 1 1 1
91 1 1 1 1 1 1 1 1 1 1 1 1 1
...
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MAPLE
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A236830 := (n, k) -> add(combinat:-fibonacci(2*i-1)*binomial(2*n-2-k-i, n-k-i), i = 0..n-k): seq(seq(A236830(n, k), k = 0..n), n = 0..10); # Peter Bala, Feb 18 2018
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MATHEMATICA
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(* The function RiordanArray is defined in A256893. *)
c[x_] := (1 - Sqrt[1 - 4 x])/(2 x);
Table[Sum[Binomial[2*n-k-j-2, n-k-j]*Fibonacci[2*j-1], {j, 0, n-k}], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Jul 18 2019 *)
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PROG
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(PARI) T(n, k) = sum(j=0, n-k, binomial(2*n-k-j-2, n-k-j)*fibonacci(2*j -1));
for(n=0, 12, for(k=0, n, print1(T(n, k), ", "))) \\ G. C. Greubel, Jul 18 2019
(Magma) [(&+[Binomial(2*n-k-j-2, n-k-j)*Fibonacci(2*j-1): j in [0..n-k]]): k in [0..n], n in [0..12]]; // G. C. Greubel, Jul 18 2019
(Sage) [[sum( binomial(2*n-k-j-2, n-k-j)*fibonacci(2*j -1) for j in (0..n-k) ) for k in (0..n)] for n in (0..12)] # G. C. Greubel, Jul 18 2019
(GAP) Flat(List([0..12], n-> List([0..n], k-> Sum([0..n-k], j-> Binomial(2*n-k-j-2, n-k-j)*Fibonacci(2*j-1) )))); # G. C. Greubel, Jul 18 2019
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CROSSREFS
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Cf. (columns): A165201, A026726, A026671, A026674, A026672, A026675, A026673, A026843, A026842 or A026846 or A026849, A026844, A026841 or A026848.
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KEYWORD
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AUTHOR
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STATUS
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approved
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