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%I M4244 #25 Feb 28 2023 21:09:23
%S 1,6,43,336,2864,25326,223034,1890123,15115098,112980937,787320629,
%T 5121184083,31188412225,178517111561,964196387369,4933278065881,
%U 23997707450765,111358094980387,494444748602595,2106504840061571
%N Number of 6-covers of an unlabeled n-set.
%C Number of 6 X n binary matrices with at least one 1 in every column up to row and column permutations.
%D R. J. Clarke, Covering a set by subsets, Discrete Math., 81 (1990), 147-152.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Andrew Howroyd, <a href="/A005786/b005786.txt">Table of n, a(n) for n = 0..500</a>
%H Vladeta Jovovic, <a href="/A005748/a005748.pdf">Binary matrices up to row and column permutations</a>
%o (PARI) Vec(G(6, x)*(1 - x) + O(x^40)) \\ G defined in A028657. - _Andrew Howroyd_, Feb 28 2023
%Y Column 6 of A055080.
%Y Cf. A002620, A005783, A005784, A005785, A055066.
%K nonn
%O 0,2
%A _N. J. A. Sloane_
%E More terms from _Vladeta Jovovic_, Jun 12 2000
%E a(0)=1 prepended by _Alois P. Heinz_, Aug 08 2022
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