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A052575
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E.g.f. (1-x)/(1-2x-2x^2+2x^3).
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0
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1, 1, 8, 48, 528, 6240, 95040, 1632960, 32578560, 725760000, 18027878400, 491774976000, 14645952921600, 472356889804800, 16409046682828800, 610694391250944000, 24244324628299776000, 1022626965270822912000
(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 518
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FORMULA
| E.g.f.: -(-1+x)/(1-2*x-2*x^2+2*x^3)
Recurrence: {a(1)=1, a(0)=1, a(2)=8, (12+2*n^3+12*n^2+22*n)*a(n) +(-2*n^2-10*n-12)*a(n+1) +(-2*n-6)*a(n+2) +a(n+3)=0}
Sum(-1/37*(-5+9*_alpha^2-12*_alpha)*_alpha^(-1-n), _alpha=RootOf(2*_Z^3-2*_Z^2-2*_Z+1))*n!
a(n) = n!*A052528(n). - R. J. Mathar, Nov 27 2011
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MAPLE
| spec := [S, {S=Sequence(Prod(Z, Union(Z, Z, Sequence(Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A165506 A165748 A072169 * A108214 A181276 A010568
Adjacent sequences: A052572 A052573 A052574 * A052576 A052577 A052578
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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