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A052651
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E.g.f. (1-x)/(1-x-x^3-x^4+x^5).
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0
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1, 0, 0, 6, 48, 120, 1440, 25200, 282240, 2903040, 50803200, 958003200, 16286054400, 305124019200, 6887085004800, 160843947264000, 3807947759616000, 98169730154496000, 2746618319757312000
(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 598
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FORMULA
| E.g.f.: -(-1+x)/(1-x-x^4+x^5-x^3)
Recurrence: {a(1)=0, a(0)=1, a(2)=0, a(3)=6, a(4)=48, (n^5+15*n^4+274*n+120+85*n^3+225*n^2)*a(n)+(-14*n^3-71*n^2-154*n-120-n^4)*a(n+1)+(-12*n^2-47*n-60-n^3)*a(n+2)+(-5-n)*a(n+4)+a(n+5)=0}
Sum(1/8519*(138+2003*_alpha-346*_alpha^2-444*_alpha^3+11*_alpha^4)*_alpha^(-1-n), _alpha=RootOf(1-_Z-_Z^4+_Z^5-_Z^3))*n!
a(n)= n!*A052532(n). - R. J. Mathar, Nov 27 2011
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MAPLE
| spec := [S, {S=Sequence(Prod(Z, Z, Z, Union(Z, Sequence(Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A192887 A000252 A078237 * A153796 A167547 A005353
Adjacent sequences: A052648 A052649 A052650 * A052652 A052653 A052654
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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