A052853 A simple grammar.

0, 1, 2, 5, 14, 42, 138, 466, 1643, 5919, 21773, 81279, 307483, 1175352, 4534161, 17626999, 68992703, 271641249, 1075144364, 4275274867, 17071822275, 68428152475, 275217386092, 1110375948303, 4492641333003, 18225081419544, 74111194585752, 302040709982249

Offset: 0

Author

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

Keywords

• easy
• nonn

Links

• Robert Israel, Table of n, a(n) for n = 0..1000
• INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 821

Crossrefs

Cf. A000010, A050383.

Programs

Maple

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

Formula

G.f. appears to be -Sum_{j>=1} (phi(j)/j) * log(1-C(x^j)), where phi = A000010 and C is the g.f. of A050383. - Robert Israel, Nov 01 2016