Search: a034349 -id:a034349
|
|
A034253
|
|
Triangle read by rows: T(n,k) = number of inequivalent linear [n,k] binary codes without 0 columns (n >= 1, 1 <= k <= n).
|
|
+10
38
|
|
|
1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 6, 4, 1, 1, 6, 12, 11, 5, 1, 1, 7, 21, 27, 17, 6, 1, 1, 9, 34, 63, 54, 25, 7, 1, 1, 11, 54, 134, 163, 99, 35, 8, 1, 1, 13, 82, 276, 465, 385, 170, 47, 9, 1, 1, 15, 120, 544, 1283, 1472, 847, 277, 61, 10, 1, 1, 18, 174, 1048, 3480
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,5
|
|
COMMENTS
|
"A linear (n, k)-code has columns of zeros, if and only if there is some i ∈ n such that x_i = 0 for all codewords x, and so we should exclude such columns." [Fripertinger and Kerber (1995, p. 196)] - Petros Hadjicostas, Sep 30 2019
|
|
LINKS
|
Discrete algorithms at the University of Bayreuth, Symmetrica.
H. Fripertinger and A. Kerber, Isometry classes of indecomposable linear codes. In: G. Cohen, M. Giusti, T. Mora (eds), Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, 11th International Symposium, AAECC 1995, Lect. Notes Comp. Sci. 948 (1995), pp. 194-204. [Here S_{nk2} = T(n,k).]
|
|
FORMULA
|
T(n,k=2) = floor(n/2) + floor((n^2 + 6)/12) = A253186(n).
G.f. for column k=2: (x^3 - x - 1)*x^2/((x^2 + x + 1)*(x + 1)*(x - 1)^3).
G.f. for column k=3: (x^12 - 2*x^11 + x^10 - x^9 - x^6 + x^4 - x - 1)*x^3/((x^6 + x^5 + x^4 + x^3 + x^2 + x + 1)*(x^2 + x + 1)^2*(x^2 + 1)*(x + 1)^2*(x - 1)^7).
G.f. for column k >= 4: modify the Sage program below (cf. function f). It is too complicated to write it here. See also some of the links above.
(End)
|
|
EXAMPLE
|
Triangle T(n,k) (with rows n >= 1 and columns k >= 1) begins as follows:
1;
1 1;
1 2 1;
1 3 3 1;
1 4 6 4 1;
1 6 12 11 5 1;
1, 7, 21, 27, 17, 6, 1;
1, 9, 34, 63, 54, 25, 7, 1;
1, 11, 54, 134, 163, 99, 35, 8, 1;
...
|
|
PROG
|
(Sage) # Fripertinger's method to find the g.f. of column k >= 2 (for small k):
def A034253col(k, length):
G1 = PSL(k, GF(2))
G2 = PSL(k-1, GF(2))
D1 = G1.cycle_index()
D2 = G2.cycle_index()
f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
f = f1 - f2
return f.taylor(x, 0, length).list()
# For instance the Taylor expansion for column k = 4 gives
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|
|
A034344
|
|
Number of binary [ n,3 ] codes without 0 columns.
|
|
+10
13
|
|
|
0, 0, 1, 3, 6, 12, 21, 34, 54, 82, 120, 174, 244, 337, 458, 613, 808, 1056, 1361, 1738, 2200, 2759, 3431, 4240, 5198, 6333, 7670, 9235, 11056, 13175, 15618, 18432, 21660, 25347, 29543, 34312, 39702, 45786, 52633, 60315, 68910, 78515, 89206, 101092, 114276, 128866, 144978, 162750, 182298
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,4
|
|
COMMENTS
|
The g.f. function below was calculated in Sage (using Fripertinger's method) and compared with the one in Lisonek's (2007) Example 5.3 (p. 627). - Petros Hadjicostas, Oct 02 2019
|
|
LINKS
|
Discrete algorithms at the University of Bayreuth, Symmetrica.
H. Fripertinger and A. Kerber, Isometry classes of indecomposable linear codes. In: G. Cohen, M. Giusti, T. Mora (eds), Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, 11th International Symposium, AAECC 1995, Lect. Notes Comp. Sci. 948 (1995), pp. 194-204. [Here a(n) = S_{n,3,2}.]
|
|
FORMULA
|
G.f.: (x^12 - 2*x^11 + x^10 - x^9 - x^6 + x^4 - x - 1)*x^3/((x^6 + x^5 + x^4 + x^3 + x^2 + x + 1)*(x^2 + x + 1)^2*(x^2 + 1)*(x + 1)^2*(x - 1)^7) = (-x^15 + 2*x^14 - x^13 + x^12 + x^9 - x^7 + x^4 + x^3)/((1 - x)^2*(-x^2 + 1)*(-x^3 + 1)^2*(-x^4 + 1)*(-x^7 + 1)). - Petros Hadjicostas, Oct 02 2019
|
|
PROG
|
(Sage) # Fripertinger's method to find the g.f. of column k >= 2 of A034253 (for small k):
def A034253col(k, length):
G1 = PSL(k, GF(2))
G2 = PSL(k-1, GF(2))
D1 = G1.cycle_index()
D2 = G2.cycle_index()
f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
f = f1 - f2
return f.taylor(x, 0, length).list()
# For instance the Taylor expansion for column k = 3 (this sequence) gives
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|
|
A034345
|
|
Number of binary [ n,4 ] codes without 0 columns.
|
|
+10
7
|
|
|
0, 0, 0, 1, 4, 11, 27, 63, 134, 276, 544, 1048, 1956, 3577, 6395, 11217, 19307, 32685, 54413, 89225, 144144, 229647, 360975, 560259, 858967, 1301757, 1950955, 2893102, 4246868, 6174084, 8892966, 12696295, 17973092, 25237467, 35163431, 48629902, 66774760, 91063984
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,5
|
|
COMMENTS
|
"We say that the sequence (a_n) is quasi-polynomial in n if there exist polynomials P_0, ..., P_{s-1} and an integer n_0 such that, for all n >= n_0, a_n = P_i(n) where i == n (mod s)." [This is from the abstract of Lisonek (2007), and he states that the condition "n >= n_0" makes his definition broader than the one in Stanley's book. From Section 5 of his paper, we conclude that (a(n): n >= 1) is a quasi-polynomial in n.] - Petros Hadjicostas, Oct 02 2019
|
|
LINKS
|
Discrete algorithms at the University of Bayreuth, Symmetrica.
H. Fripertinger and A. Kerber, Isometry classes of indecomposable linear codes. In: G. Cohen, M. Giusti, T. Mora (eds), Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, 11th International Symposium, AAECC 1995, Lect. Notes Comp. Sci. 948 (1995), pp. 194-204. [Here a(n) = S_{n,4,2}.]
|
|
PROG
|
(Sage) # Fripertinger's method to find the g.f. of column k >= 2 of A034253 (for small k):
def A034253col(k, length):
G1 = PSL(k, GF(2))
G2 = PSL(k-1, GF(2))
D1 = G1.cycle_index()
D2 = G2.cycle_index()
f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
f = f1 - f2
return f.taylor(x, 0, length).list()
# For instance the Taylor expansion for column k = 4 (this sequence) gives
print(A034253col(4, 30)) #
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|
|
A034346
|
|
Number of binary [ n,5 ] codes without 0 columns.
|
|
+10
7
|
|
|
0, 0, 0, 0, 1, 5, 17, 54, 163, 465, 1283, 3480, 9256, 24282, 62812, 160106, 401824, 992033, 2406329, 5730955, 13393760, 30709772, 69079030, 152473837, 330344629, 702839150, 1469214076, 3019246455, 6103105779, 12142291541, 23790590387, 45932253637, 87434850942, 164188881007
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,6
|
|
LINKS
|
Discrete algorithms at the University of Bayreuth, Symmetrica.
H. Fripertinger and A. Kerber, Isometry classes of indecomposable linear codes. In: G. Cohen, M. Giusti, T. Mora (eds), Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, 11th International Symposium, AAECC 1995, Lect. Notes Comp. Sci. 948 (1995), pp. 194-204. [Here a(n) = S_{n,5,2}.]
|
|
PROG
|
(Sage) # Fripertinger's method to find the g.f. of column k >= 2 (for small k):
def A034253col(k, length):
G1 = PSL(k, GF(2))
G2 = PSL(k-1, GF(2))
D1 = G1.cycle_index()
D2 = G2.cycle_index()
f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
f = f1 - f2
return f.taylor(x, 0, length).list()
# For instance the Taylor expansion for column k = 5 gives a(n):
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|
|
A034347
|
|
Number of binary [ n,6 ] codes without 0 columns.
|
|
+10
7
|
|
|
0, 0, 0, 0, 0, 1, 6, 25, 99, 385, 1472, 5676, 22101, 87404, 350097, 1413251, 5708158, 22903161, 90699398, 352749035, 1342638839, 4990325414, 18090636016, 63933709870, 220277491298, 740170023052, 2426954735273, 7770739437179, 24314436451415, 74406425640743, 222867051758565, 653898059035166
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,7
|
|
LINKS
|
Discrete algorithms at the University of Bayreuth, Symmetrica.
H. Fripertinger and A. Kerber, Isometry classes of indecomposable linear codes. In: G. Cohen, M. Giusti, T. Mora (eds), Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, 11th International Symposium, AAECC 1995, Lect. Notes Comp. Sci. 948 (1995), pp. 194-204. [Here a(n) = S_{n,6,2}.]
|
|
PROG
|
(Sage) # Fripertinger's method to find the g.f. of column k >= 2 of A034253 (for small k):
def A034253col(k, length):
G1 = PSL(k, GF(2))
G2 = PSL(k-1, GF(2))
D1 = G1.cycle_index()
D2 = G2.cycle_index()
f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
f = f1 - f2
return f.taylor(x, 0, length).list()
# For instance the Taylor expansion for column k = 6 (this sequence gives
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|
|
A034348
|
|
Number of binary [ n,7 ] codes without 0 columns.
|
|
+10
7
|
|
|
0, 0, 0, 0, 0, 0, 1, 7, 35, 170, 847, 4408, 24297, 143270, 901491, 5985278, 41175203, 287813284, 2009864185, 13848061942, 93369988436, 613030637339, 3908996099141, 24179747870890, 145056691643428, 844229016035010, 4769751989333029, 26181645303024760, 139750488576152520
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,8
|
|
COMMENTS
|
To find the g.f., modify the Sage program below (cf. function f). It is very complicated to write it here. - Petros Hadjicostas, Oct 05 2019
|
|
LINKS
|
Discrete algorithms at the University of Bayreuth, Symmetrica.
H. Fripertinger and A. Kerber, Isometry classes of indecomposable linear codes. In: G. Cohen, M. Giusti, T. Mora (eds), Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, 11th International Symposium, AAECC 1995, Lect. Notes Comp. Sci. 948 (1995), pp. 194-204. [Here a(n) = S_{n,7,2}.]
|
|
PROG
|
(Sage) # Fripertinger's method to find the g.f. of column k >= 2 of A034253 (for small k):
def A034253col(k, length):
G1 = PSL(k, GF(2))
G2 = PSL(k-1, GF(2))
D1 = G1.cycle_index()
D2 = G2.cycle_index()
f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
f = f1 - f2
return f.taylor(x, 0, length).list()
# For instance the Taylor expansion for column k = 7 (this sequence) gives
print(A034253col(7, 30)) #
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|
|
A034362
|
|
Number of binary [ n,8 ] codes.
|
|
+10
3
|
|
|
0, 0, 0, 0, 0, 0, 0, 1, 9, 56, 333, 2108, 14724, 117169, 1074526, 11249092, 130484439, 1612782351, 20497233072, 260975054461, 3273854883027, 40073904283055, 476142523109291, 5477680380616386, 60959857679340812
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,9
|
|
REFERENCES
|
H. Fripertinger and A. Kerber, in AAECC-11, Lect. Notes Comp. Sci. 948 (1995), 194-204.
|
|
LINKS
|
|
|
CROSSREFS
|
Column k=8 of both A034356 and A076831 (which are the same except for column k=0).
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
Search completed in 0.011 seconds
|