A052826 A simple grammar: product of cycles and cycles of cycles.

0, 0, 2, 9, 48, 315, 2497, 23394, 254132, 3149826, 43945354, 682314028, 11676044036, 218402171520, 4433885571840, 97098961376112, 2281563329170752, 57255174735315792, 1528204674443305680, 43227315891291907488, 1291646719998952196448, 40652195494651491747840

Offset

0,3

Links

Table of n, a(n) for n=0..21.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 791

Formula

E.g.f.: log(-1/(-1+x))*log(-1/(-1+log(-1/(-1+x)))).

Maple

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

Crossrefs

Sequence in context: A357790 A205571 A354312 * A358264 A375795 A246759

Adjacent sequences: A052823 A052824 A052825 * A052827 A052828 A052829

Keyword

easy,nonn

Author

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

Extensions

More terms from Alois P. Heinz, Mar 16 2016

Status

approved