OFFSET
0,3
LINKS
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 797
FORMULA
E.g.f.: log((-1+x)/(-1+x+x^2)).
Recurrence: {a(1)=0, a(3)=6, a(2)=2, (n^3+3*n^2+2*n)*a(n)+(-4-2*n)*a(n+2)+a(n+3)}.
(RootOf(_Z^2-_Z-1)^n*RootOf(_Z^2-_Z-1)+(1-RootOf(_Z^2-_Z-1))^(n+1)-1)*GAMMA(n+1)/RootOf(_Z^2-_Z-1)/(-1+RootOf(_Z^2-_Z-1)).
MAPLE
spec := [S, {B=Prod(Z, C), C=Sequence(Z, 1 <= card), S= Cycle(B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
EXTENSIONS
More terms from Alois P. Heinz, Mar 16 2016
STATUS
approved