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Search: id:A057966
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| A057966 |
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Triangle T(n,k) of number of minimal 5-covers of a labeled n-set that cover k points of that set uniquely (k=5,..,n). |
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4
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| 1, 156, 15, 14196, 2730, 140, 984256, 283920, 29120, 1050, 57578976, 22145760, 3407040, 245700, 6951, 2994106752, 1439474400, 295276800, 31941000, 1807260, 42525, 142719088512, 82337935680, 21112291200, 3045042000, 258438180
(list; table; graph; listen)
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OFFSET
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5,2
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COMMENT
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Row sums give A046166.
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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], [156, 15], [14196, 2730, 140], [984256, 283920, 29120, 1050], ...; there are 15 minimal 5-covers of a labeled 6-set that cover 6 points of that set uniquely.
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CROSSREFS
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Cf. A035347, A057669, A057963-A057965, A057967, A057968(unlabeled case).
Sequence in context: A110834 A110842 A115466 this_sequence A112818 A047635 A052477
Adjacent sequences: A057963 A057964 A057965 this_sequence A057967 A057968 A057969
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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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