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Search: id:A052898
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| 3, 3, 5, 13, 49, 241, 1441, 10081, 80641, 725761, 7257601, 79833601, 958003201, 12454041601, 174356582401, 2615348736001, 41845579776001, 711374856192001, 12804747411456001, 243290200817664001
(list; graph; listen)
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OFFSET
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0,1
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 874
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FORMULA
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E.g.f.: (-2-exp(x)+x*exp(x))/(-1+x)
Recurrence: {a(2)=5, a(1)=3, (n^2+2*n+1)*a(n)+(-n^2-3*n-1)*a(n+1)+a(n+2)*n}
2n! + 1.
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MAPLE
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spec := [S, {S=Union(Sequence(Z), Sequence(Z), Set(Z))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Adjacent sequences: A052895 A052896 A052897 this_sequence A052899 A052900 A052901
Sequence in context: A126318 A079439 A133190 this_sequence A095355 A069834 A064038
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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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