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A005786
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Number of 6-covers of an unlabeled n-set.
(Formerly M4244)
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7
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1, 6, 43, 336, 2864, 25326, 223034, 1890123, 15115098, 112980937, 787320629, 5121184083, 31188412225, 178517111561, 964196387369, 4933278065881, 23997707450765, 111358094980387, 494444748602595, 2106504840061571
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OFFSET
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0,2
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COMMENTS
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Number of 6 X n binary matrices with at least one 1 in every column up to row and column permutations.
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REFERENCES
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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).
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LINKS
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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