A052828 A simple grammar: union of cycles and cycles of cycles.

0, 2, 3, 9, 41, 252, 1954, 18302, 200906, 2528152, 35862456, 565985472, 9834073248, 186504365616, 3833188731072, 84862243895088, 2013237501351504, 50950031663224320, 1370088133344414336, 39011485705595544960, 1172540863138831491456, 37097659139410654988544

Offset

0,2

Links

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

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 793

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

Crossrefs

Sequence in context: A125052 A181139 A162093 * A214915 A219673 A012972

Adjacent sequences: A052825 A052826 A052827 * A052829 A052830 A052831

Keyword

easy,nonn

Author

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

Extensions

More terms from Alois P. Heinz, Mar 16 2016

Status

approved