A055066 Number of 7-covers of an unlabeled n-set.

1, 7, 62, 664, 8609, 127415, 2004975, 31500927, 474504448, 6708348262, 88249739792, 1078567590128, 12269901302433, 130370516668917, 1298891291366245, 12182760243381355, 107979270564656625, 907568508195185203, 7256984238345563764, 55365443728411530716, 404091280028746802188

Offset

0,2

Comments

Number of 7 X n binary matrices with at least one 1 in every column up to row and column permutations. - Andrew Howroyd, Feb 28 2023

Links

Andrew Howroyd, Table of n, a(n) for n = 0..1000

Vladeta Jovovic, Binary matrices up to row and column permutations

Prog

(PARI) Vec(G(7, x)*(1-x) + O(x^40)) \\ G defined in A028657. - Andrew Howroyd, Feb 28 2023

Crossrefs

Column 7 of A055080.

Cf. A005748, A002620, A005783, A005784, A005785, A005786.

Sequence in context: A287481 A289212 A060005 * A216534 A167550 A304895

Adjacent sequences: A055063 A055064 A055065 * A055067 A055068 A055069

Keyword

nonn

Author

Vladeta Jovovic, Jun 12 2000

Extensions

a(0)=1 prepended by Alois P. Heinz, Aug 08 2022

Terms a(17) and beyond from Andrew Howroyd, Feb 28 2023

Status

approved