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

0,3

Links

Robert Israel, Table of n, a(n) for n = 0..1000

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 821

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

Maple

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

Crossrefs

Cf. A000010, A050383.

Sequence in context: A360708 A148331 A306422 * A380237 A149877 A149878

Adjacent sequences: A052850 A052851 A052852 * A052854 A052855 A052856

Keyword

easy,nonn

Author

INRIA Encyclopedia of Combinatorial Structures, Jan 25 2000

Status

approved