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A052765
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A simple grammar.
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0
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0, 0, 0, 0, 0, 120, 1080, 8820, 75600, 701568, 7091280, 77961840, 928778400, 11937347136, 164802429792, 2433765035520, 38299272560640, 639999894048768, 11320441140625920, 211340086405770240
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,6
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 722
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FORMULA
| E.g.f.: x^2*ln(-1/(-1+x))^3
Recurrence: {a(1)=0, a(2)=0, a(4)=0, a(3)=0, (16*n-48*n^2-4*n^3-n^6+13*n^4+48)*a(n)+(n^2+61*n-26*n^3+3*n^4+3*n^5-42)*a(n+1)+(-9*n+15*n^2-3*n^3-3*n^4)*a(n+2)+(n^3-n)*a(n+3), a(5)=120}
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MAPLE
| spec := [S, {B=Cycle(Z), S=Prod(Z, Z, B, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A092182 A133119 A052777 * A167549 A052776 A052770
Adjacent sequences: A052762 A052763 A052764 * A052766 A052767 A052768
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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