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A052678
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E.g.f. x^3/(1-3x).
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0
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0, 0, 0, 6, 72, 1080, 19440, 408240, 9797760, 264539520, 7936185600, 261894124800, 9428188492800, 367699351219200, 15443372751206400, 694951773804288000, 33357685142605824000, 1701241942272897024000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 626
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FORMULA
| E.g.f.: -x^3/(-1+3*x)
Recurrence: {a(1)=0, a(0)=0, a(2)=0, a(3)=6, (-3*n-3)*a(n)+a(n+1)=0}
3^(n-3)*n!, n>2.
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MAPLE
| spec := [S, {S=Prod(Z, Z, Z, Sequence(Union(Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A067419 A113331 A156128 * A052719 A196882 A063965
Adjacent sequences: A052675 A052676 A052677 * A052679 A052680 A052681
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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