OFFSET
0,4
COMMENTS
Apart from a(3), the same as A052732. - R. J. Mathar, Oct 16 2013
LINKS
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 689
FORMULA
D-finite with recurrence: a(1)=0; a(2)=0; a(3)=6; a(4)=24; -2*(n+1)*(2*n-5)*a(n)+(n-1)*a(n+1) =0.
a(n) = n!*A000108(n-3). - R. J. Mathar, Oct 16 2013
G.f.: x^2*(1- 2F0(-1/2,3;;4*x)). - R. J. Mathar, Jan 25 2020
MAPLE
spec := [S, {B=Union(Z, C), C=Prod(B, B), S=Prod(B, Z, Z)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
PROG
(MuPAD) combinat::catalan(n)*(n+3)! $ n = 0..15; // Zerinvary Lajos, Feb 15 2007
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
STATUS
approved