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A052766
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A simple grammar.
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0
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0, 0, 0, 0, 0, 120, 720, 4620, 33600, 276192, 2540160, 25874640, 289301760, 3523208832, 46425899520, 658169366400, 9988896153600, 161590513766400, 2775695618949120, 50455787382604800, 967644983144448000
(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 723
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FORMULA
| E.g.f.: ln(-1/(-1+x))^2*x^3
Recurrence: {a(1)=0, a(2)=0, a(4)=0, a(3)=0, a(5)=120, (n^4-7*n^2-3*n^3+15*n+18)*a(n)+(8*n-2*n^3+5*n^2-20)*a(n+1)+(-3*n+n^2+2)*a(n+2)}
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MAPLE
| spec := [S, {B=Cycle(Z), S=Prod(Z, Z, Z, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A052787 A052769 A179724 * A052627 A206025 A029573
Adjacent sequences: A052763 A052764 A052765 * A052767 A052768 A052769
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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