A005747 Number of n-covers of an unlabeled 6-set.

1, 16, 196, 2197, 22952, 223034, 2004975, 16642937, 127654604, 907349654, 6000728764, 37093282121, 215296646264, 1178514299094, 6108871834312, 30098215339608, 141433252447082, 635816643771438, 2742163498527536, 11374522802412498, 45482770393453638

Offset: 1

Author

N. J. A. Sloane, Simon Plouffe

Keywords

• nonn

Comments

Number of n X 6 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 A055084.

Programs

PARI

Vec((G(6, x) - G(5, x)) + O(x^30)) \\ G defined in A028657. - Andrew Howroyd, Feb 28 2023

Extensions

Corrected and extended by Vladeta Jovovic, Jun 13 2000

Terms a(20) and beyond from Andrew Howroyd, Feb 28 2023