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Search: id:A057965
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| A057965 |
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Triangle T(n,k) of number of minimal 4-covers of a labeled n-set that cover k points of that set uniquely (k=4,..,n). |
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5
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| 1, 55, 10, 1815, 660, 65, 46585, 25410, 5005, 350, 1024870, 745360, 220220, 30800, 1701, 20292426, 18447660, 7267260, 1524600, 168399, 7770, 372027810, 405848520, 199849650, 55902000, 9261945, 854700, 34105, 6430766430
(list; table; graph; listen)
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OFFSET
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4,2
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COMMENT
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Row sums give A016111.
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LINKS
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Eric Weisstein's World of Mathematics, Minimal cover
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FORMULA
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Number of minimal m-covers of a labeled n-set that cover k points of that set uniquely is C(n, k)*S(k, m)*(2^m-m-1)^(n-k), where S(k, m) are Stirling numbers of the second kind.
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EXAMPLE
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[1], [55, 10], [1815, 660, 65], [46585, 25410, 5005, 350], ...; there are 1815 minimal 4-covers of a labeled 6-set that cover 4 points of that set uniquely.
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CROSSREFS
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Cf. A035347, A057669, A057963, A057964, A057966, A057967(unlabeled case), A057968.
Sequence in context: A151635 A159732 A012854 this_sequence A083516 A033375 A112892
Adjacent sequences: A057962 A057963 A057964 this_sequence A057966 A057967 A057968
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KEYWORD
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easy,nonn,tabl
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 17 2000
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