A005747 Number of n-covers of an unlabeled 6-set. (Formerly M5018)

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

Offset

1,2

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

Prog

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

Crossrefs

A diagonal of A055080.

First differences give A055084.

Sequence in context: A126981 A086940 A016173 * A103721 A144844 A093060

Adjacent sequences: A005744 A005745 A005746 * A005748 A005749 A005750

Keyword

nonn

Author

N. J. A. Sloane, Simon Plouffe

Extensions

Corrected and extended by Vladeta Jovovic, Jun 13 2000

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

Status

approved