A056037 Number of 6x6 binary matrices with n ones, with no zero rows or columns, up to row and column permutation.

1, 2, 15, 69, 288, 840, 2144, 4488, 8317, 13160, 18636, 23078, 25856, 25623, 23187, 18713, 13932, 9288, 5816, 3256, 1767, 858, 419, 180, 88, 34, 16, 6, 3, 1, 1

Offset

6,2

Comments

Sum_{k=0..36} a(n)=A054976(6).

Links

Table of n, a(n) for n=6..36.

Formula

G.f. : Z(S_6 X S_6; x_1, x_2, ...)-2*Z(S_6 X S_5; x_1, x_2, ...)+Z(S_5 X S_5; 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. A052370.

Sequence in context: A216614 A146757 A091135 * A125903 A268644 A178321

Adjacent sequences: A056034 A056035 A056036 * A056038 A056039 A056040

Keyword

fini,full,nonn

Author

Vladeta Jovovic, Aug 04 2000

Status

approved