A005771 Number of n-covers of an unlabeled 5-set. (Formerly M4856)

1, 12, 103, 736, 4571, 25326, 127415, 588687, 2518997, 10053739, 37656707, 133084998, 445949359, 1422934989, 4340110439, 12697803333, 35744330644, 97081519369, 255032046536, 649459943602, 1606518048420, 3867119228081, 9073566868140, 20783186834063

Offset

1,2

Comments

Number of n X 5 binary matrices with at least one 1 in every column up to row and column permutations. - Andrew Howroyd, Feb 28 2023

References

R. J. Clarke, Covering a set by subsets, Discrete Math., 81 (1990), 147-152.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Andrew Howroyd, Table of n, a(n) for n = 1..1000

Vladeta Jovovic, Binary matrices up to row and column permutations

Formula

a(n) = A052264(n) - A006148(n). - Andrew Howroyd, Feb 28 2023

Prog

(PARI) Vec(G(5, x) - G(4, x) + O(x^40)) \\ G defined in A028657. - Andrew Howroyd, Feb 28 2023

Crossrefs

A diagonal of A055080.

First differences give A055083.

Cf. A006148, A052264.

Sequence in context: A052067 A307821 A050791 * A016228 A016276 A264452

Adjacent sequences: A005768 A005769 A005770 * A005772 A005773 A005774

Keyword

nonn

Author

N. J. A. Sloane, Simon Plouffe

Extensions

More terms from Vladeta Jovovic, Jun 13 2000

Terms a(21) and beyond from Andrew Howroyd, Feb 28 2023

Status

approved