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A052632
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E.g.f. 1/(1-x-x^5).
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0
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1, 1, 2, 6, 24, 240, 2160, 20160, 201600, 2177280, 29030400, 439084800, 7185024000, 124540416000, 2266635571200, 44460928512000, 941525544960000, 21341245685760000, 512189896458240000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 578
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FORMULA
| E.g.f.: -1/(-1+x^5+x)
Recurrence: {a(1)=1, a(0)=1, a(3)=6, a(2)=2, a(4)=24, (-n^5-15*n^4-274*n-120-85*n^3-225*n^2)*a(n) +(-5-n)*a(n+4) +a(n+5)=0}
Sum(1/3381*(256+320*_alpha^4+400*_alpha^3+500*_alpha^2+625*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+_Z^5+_Z))*n!
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MAPLE
| spec := [S, {S=Sequence(Union(Z, Prod(Z, Z, Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A052699 A074351 A052597 * A052692 A052723 A114778
Adjacent sequences: A052629 A052630 A052631 * A052633 A052634 A052635
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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