A052601 E.g.f. (1-x)/(1-x-2x^3).

1, 0, 0, 12, 48, 240, 4320, 50400, 564480, 9434880, 166924800, 2953843200, 60354201600, 1357490534400, 31907254579200, 808142759424000, 22052620541952000, 635257746579456000, 19347973338710016000

Offset

0,4

Links

Table of n, a(n) for n=0..18.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 546

Formula

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

Recurrence: {a(1)=0, a(0)=1, a(2)=0, (-12*n^2-22*n-12-2*n^3)*a(n) +(-n-3)*a(n+2) +a(n+3)=0}

Sum(-1/29*(1+3*_alpha^2-10*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+_Z+2*_Z^3))*n!

a(n)= n!*A052537(n). - R. J. Mathar, Nov 27 2011

Maple

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

Crossrefs

Sequence in context: A221908 A242026 A340727 * A003498 A326743 A269030

Adjacent sequences: A052598 A052599 A052600 * A052602 A052603 A052604

Keyword

easy,nonn

Author

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

Status

approved