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Search: id:A052888
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| 0, 1, 3, 19, 189, 2576, 44683, 941977, 23388025, 668520163, 21622993111, 780789908240, 31135480907413, 1358965445353621, 64440211018897379, 3298807094967155971, 181322497435007616497, 10651131815012588324380
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 863
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FORMULA
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E.g.f.: RootOf(_Z-exp(exp(_Z)*x)+1)
a(n) = Sum_{k=1..n} Stirling2(n, k)*n^(k-1). - Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 26 2005
a(n) = exp(-n)*Sum_{k>1} n^(k-1)*k^n/k!. - Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 03 2006
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MAPLE
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spec := [S, {C=Prod(Z, B), B=Set(S), S=Set(C, 1 <= card)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A121083 A006531 A143633 this_sequence A141623 A090354 A119394
Adjacent sequences: A052885 A052886 A052887 this_sequence A052889 A052890 A052891
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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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