A052652 E.g.f. x^4/(1-2x).

0, 0, 0, 0, 24, 240, 2880, 40320, 645120, 11612160, 232243200, 5109350400, 122624409600, 3188234649600, 89270570188800, 2678117105664000, 85699747381248000, 2913791410962432000, 104896490794647552000

Offset

0,5

Links

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

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 599

Formula

E.g.f.: -x^4/(-1+2*x)

Recurrence: {a(1)=0, a(0)=0, a(2)=0, a(3)=0, (-2*n-2)*a(n)+a(n+1)=0, a(4)=24}

2^(n-4)*n!, n>3.

Maple

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

Mathematica

With[{nn=20}, CoefficientList[Series[x^4/(1-2x), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Mar 30 2017 *)

Crossrefs

Sequence in context: A357242 A000536 A151720 * A052732 A267060 A086603

Adjacent sequences: A052649 A052650 A052651 * A052653 A052654 A052655

Keyword

easy,nonn

Author

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

Status

approved