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Search: id:A052845
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| A052845 |
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E.g.f.: exp(x^2/(1-x)). |
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+0
8
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| 1, 0, 2, 6, 36, 240, 1920, 17640, 183120, 2116800, 26943840, 374220000, 5628934080, 91122071040, 1579034096640, 29155689763200, 571308920582400, 11838533804697600, 258608278645516800, 5938673374272038400
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Number of partitions of {1,..,n} into any number of lists of size >1, where a list means an ordered subset, cf. A000262. - Vladeta Jovovic, Vladimir Baltic (vladeta(AT)Eunet.yu), Oct 29 2002
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 813
N. J. A. Sloane, Transforms
Index entries for related partition-counting sequences
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FORMULA
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Recurrence: {a(0)=1, a(1)=0, a(2)=2, (n^2+3*n+2)*a(n)+(n^2+n-2)*a(n+1)+(-4-2*n)*a(n+2)+a(n+3)}
Inverse binomial transform of A000262: Sum_{k=0..n} (-1)^(n-k)*binomial(n, k)*A000262(k). - Vladeta Jovovic, Vladimir Baltic (vladeta(AT)Eunet.yu), Oct 29 2002
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MAPLE
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spec := [S, {B=Sequence(Z, 1 <= card), C=Prod(Z, B), S= Set(C, 1 <= card)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Adjacent sequences: A052842 A052843 A052844 this_sequence A052846 A052847 A052848
Sequence in context: A074424 A002868 A002869 this_sequence A052832 A058583 A075096
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
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Initial term changed to a(0) = 1, Apr 24 2005
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