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A052683
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E.g.f. 2x^4/(1-x).
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0
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0, 0, 0, 0, 48, 240, 1440, 10080, 80640, 725760, 7257600, 79833600, 958003200, 12454041600, 174356582400, 2615348736000, 41845579776000, 711374856192000, 12804747411456000, 243290200817664000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 631
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FORMULA
| E.g.f.: -2*x^4/(-1+x)
Recurrence: {a(1)=0, a(0)=0, a(2)=0, (-1-n)*a(n)+a(n+1)=0, a(3)=0, a(4)=48}
2*n!, n>3.
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MAPLE
| spec := [S, {S=Prod(Z, Z, Z, Sequence(Z), Union(Z, Z))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A100146 A157913 A181773 * A206054 A206047 A205469
Adjacent sequences: A052680 A052681 A052682 * A052684 A052685 A052686
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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