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A056079
Number of 7 X 7 binary matrices with n ones, with no zero rows or columns, up to row and column permutation.
4
1, 2, 15, 79, 420, 1744, 6197, 18715, 50042, 118121, 250025, 475791, 820987, 1287695, 1845875, 2423114, 2923474, 3246721, 3327677, 3150758, 2761802, 2242711, 1690526, 1183725, 771951, 469281, 267108, 142542, 71844, 34271, 15685, 6861, 2948, 1223, 513, 209, 90, 34, 16, 6, 3, 1, 1
OFFSET
7,2
COMMENTS
Sum_{k=0..49} a(n)=A054976(7).
FORMULA
G.f. : Z(S_7 X S_7; x_1, x_2, ...)-2*Z(S_7 X S_6; x_1, x_2, ...)+Z(S_6 X S_6; x_1, x_2, ...) if we replace x_i by 1+x^i, where Z(S_i X S_j; x_1, x_2, ...) is cycle index of Cartesian product of symmetric groups S_i and S_j of degree i and j, respectively.
CROSSREFS
Cf. A053304.
Sequence in context: A041243 A216247 A291972 * A266622 A036239 A268735
KEYWORD
fini,full,nonn
AUTHOR
Vladeta Jovovic, Aug 04 2000
EXTENSIONS
More terms from Sean A. Irvine, Apr 14 2022
STATUS
approved