A005771 Number of n-covers of an unlabeled 5-set.

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

Author

N. J. A. Sloane, Simon Plouffe

Keywords

• nonn

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

Crossrefs

A diagonal of A055080.

First differences give A055083.

Cf. A006148, A052264.

Programs

PARI

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

Formula

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

Extensions

More terms from Vladeta Jovovic, Jun 13 2000

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