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Search: id:A052777
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| 0, 0, 0, 0, 0, 120, 1080, 6300, 30240, 130032, 521640, 1996500, 7389360, 26676936, 94486392, 329647500, 1136116800, 3876164832, 13112135496, 44031456900, 146920942800
(list; graph; listen)
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OFFSET
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0,6
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 734
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FORMULA
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G.f.: x^2*exp(x)^3-3*x^2*exp(x)^2+3*exp(x)*x^2-x^2
Recurrence: {a(1)=0, a(2)=0, a(4)=0, a(3)=0, (-36*n^2-66*n-6*n^3-36)*a(n)+(11*n+11*n^3+44*n^2-66)*a(n+1)+(-12*n^2+18*n-6*n^3)*a(n+2)+(n^3-n)*a(n+3), a(5)=120}
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MAPLE
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spec := [S, {B=Set(Z, 1 <= card), S=Prod(Z, Z, B, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A011245 A092182 A133119 this_sequence A052765 A052776 A052770
Adjacent sequences: A052774 A052775 A052776 this_sequence A052778 A052779 A052780
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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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