A052607 E.g.f. (1-x^3)/(1-x^2-x^3).

1, 0, 2, 0, 24, 120, 720, 10080, 80640, 1088640, 14515200, 199584000, 3353011200, 56043187200, 1046139494400, 20922789888000, 439378587648000, 9959247986688000, 236887827111936000, 5960609920032768000

Offset

0,3

Links

Table of n, a(n) for n=0..19.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 552

Formula

E.g.f.: (-1+x^3)/(-1+x^2+x^3)

Recurrence: {a(1)=0, a(0)=1, a(3)=0, a(2)=2, (-11*n-6-n^3-6*n^2)*a(n) +(-n^2-5*n-6)*a(n+1) +a(n+3)=0}

Sum(-1/23*(6*_alpha^2+2*_alpha-9)*_alpha^(-1-n), _alpha=RootOf(_Z^3+_Z^2-1))*n!

Maple

spec := [S, {S=Sequence(Prod(Z, Z, Sequence(Prod(Z, Z, Z))))}, labeled]: [seq(combstruct[count](spec, size=n), n=0..20)];

Mathematica

With[{nn=20}, CoefficientList[Series[(1-x^3)/(1-x^2-x^3), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Jan 04 2012 *)

Crossrefs

Sequence in context: A127067 A174077 A365980 * A052602 A012588 A012290

Adjacent sequences: A052604 A052605 A052606 * A052608 A052609 A052610

Keyword

easy,nonn

Author

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

Status

approved