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 A052605 E.g.f. x(1-x)/(1-x-x^3). 0
 0, 1, 0, 0, 24, 120, 720, 10080, 120960, 1451520, 21772800, 359251200, 6227020800, 118313395200, 2440992153600, 53614649088000, 1255367393280000, 31300493672448000, 825906208038912000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 LINKS INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 550 FORMULA E.g.f.: x*(-1+x)/(-1+x+x^3) Recurrence: {a(1)=1, a(0)=0, a(2)=0, (-11*n-6-n^3-6*n^2)*a(n) +(-n-3)*a(n+2) +a(n+3)=0} Sum(1/31*(_alpha+11*_alpha^2-3)*_alpha^(-1-n), _alpha=RootOf(-1+_Z+_Z^3))*n! MAPLE spec := [S, {S=Prod(Z, Sequence(Prod(Z, Z, Z, Sequence(Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20); CROSSREFS Sequence in context: A342856 A293050 A052581 * A195917 A334189 A042120 Adjacent sequences:  A052602 A052603 A052604 * A052606 A052607 A052608 KEYWORD easy,nonn AUTHOR encyclopedia(AT)pommard.inria.fr, Jan 25 2000 STATUS approved

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Last modified May 14 08:44 EDT 2021. Contains 343879 sequences. (Running on oeis4.)