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 A052697 E.g.f. 1/(1-x^3-x^4). 0
 1, 0, 0, 6, 24, 0, 720, 10080, 40320, 362880, 10886400, 119750400, 958003200, 24908083200, 523069747200, 6538371840000, 125536739328000, 3556874280960000, 70426110763008000, 1338096104497152000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 646 FORMULA E.g.f.: -1/(-1+x^3+x^4) Recurrence: {a(1)=0, a(0)=1, a(2)=0, a(3)=6, (-n^4-35*n^2-50*n-24-10*n^3)*a(n)+(-n^3-9*n^2-26*n-24)*a(n+1)+a(n+4)=0} Sum(-1/283*(-16-73*_alpha+3*_alpha^2+12*_alpha^3)*_alpha^(-1-n), _alpha=RootOf(-1+_Z^3+_Z^4))*n! a(n) = n!*A017817(n). - R. J. Mathar, Nov 27 2011 MAPLE spec := [S, {S=Sequence(Prod(Z, Z, Union(Z, Prod(Z, Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20); CROSSREFS Sequence in context: A013266 A154420 A194770 * A213344 A193429 A213278 Adjacent sequences:  A052694 A052695 A052696 * A052698 A052699 A052700 KEYWORD easy,nonn AUTHOR encyclopedia(AT)pommard.inria.fr, Jan 25 2000 STATUS approved

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