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A052657 E.g.f. x^2/((1-x)^2*(1+x)). 1
0, 0, 2, 6, 48, 240, 2160, 15120, 161280, 1451520, 18144000, 199584000, 2874009600, 37362124800, 610248038400, 9153720576000, 167382319104000, 2845499424768000, 57621363351552000, 1094805903679488000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Stirling transform of -(-1)^n*a(n-1) = [0, 0, 2, -6, 48, -240, ...] is A052841(n-1) = [0, 0, 2, 6, 38, 270, ...]. - Michael Somos, Mar 04 2004

LINKS

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

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 604

FORMULA

a(0)=0, a(1)=0, a(2)=2, n*a(n+2) = (n+2)*a(n+1) + (n^3 + 4*n^2 + 5*n + 2)*a(n).

a(n) = (2n-1+(-1)^n)*n!/4 = n!*A004526(n).

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

MAPLE

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

a:=n->sum((-1)^k * (n-k+1) * n!, k=2..n) : seq(a(n), n=0..19); # Zerinvary Lajos, Jun 18 2007

PROG

(PARI) a(n)=if(n<0, 0, n!*polcoeff(x^2/(1-x)/(1-x^2)+x*O(x^n), n))

CROSSREFS

Sequence in context: A098710 A052614 A052688 * A230714 A092143 A281027

Adjacent sequences:  A052654 A052655 A052656 * A052658 A052659 A052660

KEYWORD

easy,nonn

AUTHOR

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

STATUS

approved

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Last modified February 21 04:18 EST 2019. Contains 320371 sequences. (Running on oeis4.)