A052739 E.g.f. (1-sqrt(1-4x-4x^2))/2 -x*(1+x).

0, 0, 2, 24, 288, 4800, 103680, 2741760, 85800960, 3100446720, 127037030400, 5819550105600, 294727768473600, 16350861400473600, 986127353590579200, 64238655955009536000, 4495021381191204864000, 336249161369543245824000

Offset

0,3

Links

Table of n, a(n) for n=0..17.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 695

Formula

D-finite with recurrence: a(1)=0; a(2)=2; a(3)=24; a(4)=288; (-4*n^2+4)*a(n) +(-4*n-2)*a(n+1) +a(n+2)=0.

a(n) = A052727(n), n>2.- R. J. Mathar, Jan 26 2020

Maple

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

Mathematica

With[{nn=20}, CoefficientList[Series[(1-Sqrt[1-4x-4x^2])/2-x(1+x), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Jun 19 2018 *)

Crossrefs

Sequence in context: A230129 A355951 A065101 * A135389 A336310 A065513

Adjacent sequences: A052736 A052737 A052738 * A052740 A052741 A052742

Keyword

easy,nonn

Author

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

Status

approved