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A052826 A simple grammar: product of cycles and cycles of cycles. 1
0, 0, 2, 9, 48, 315, 2497, 23394, 254132, 3149826, 43945354, 682314028, 11676044036, 218402171520, 4433885571840, 97098961376112, 2281563329170752, 57255174735315792, 1528204674443305680, 43227315891291907488, 1291646719998952196448, 40652195494651491747840 (list; graph; refs; listen; history; text; internal format)
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: A074143 A198892 A205571 * A246759 A191005 A257544

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

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Last modified September 20 04:33 EDT 2020. Contains 337264 sequences. (Running on oeis4.)