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Search: id:A095421
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| A095421 |
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Triangle read by rows: T(n,m) = number of m-block proper covers (without empty blocks and without multiple blocks) of a labeled n-set (n>=2, 2<=m<=2^n-2). |
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3
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| 1, 6, 17, 15, 6, 1, 25, 230, 861, 1918, 2975, 3428, 3003, 2002, 1001, 364, 91, 14, 1, 90, 2125, 20930, 127701, 568820, 2003635, 5820750, 14282125, 30030000, 54620475, 86490950, 119759325, 145422600, 155117515, 145422675, 119759850, 86493225
(list; graph; listen)
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OFFSET
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2,2
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
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T(n, m) = Sum((-1)^(n-i)*binomial(n, i)*binomial(2^i-1, m), i=1..n) - binomial(2^n-2, m-1).
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EXAMPLE
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1; 6,17,15,6,1; 25,230,861,1918,2975,3428,3003,2002,1001,364,91,14,1; ...
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CROSSREFS
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Cf. A007537(row sums), A055154, A055127, A055152, A095422, A095423.
Sequence in context: A120930 A070395 A112366 this_sequence A063584 A019296 A035484
Adjacent sequences: A095418 A095419 A095420 this_sequence A095422 A095423 A095424
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KEYWORD
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easy,nonn,tabf
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AUTHOR
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Goran Kilibarda, Vladeta Jovovic (vladeta(AT)Eunet.yu), Jun 04 2004
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