A052815 Number of objects generated by the Combstruct grammar defined in the Maple program. See the link for the grammar specification.

0, 1, 2, 5, 16, 56, 221, 900, 3839, 16752, 74701, 338327, 1553181, 7208191, 33768389, 159463655, 758291989, 3627890869, 17450572584, 84342086908, 409394388458, 1994883122360, 9754673396640, 47850963112328, 235413886888082, 1161267995487057, 5742484341773444

Offset

0,3

Links

Andrew Howroyd, Table of n, a(n) for n = 0..200

C. G. Bower, Transforms (2).

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 780

Maplesoft, Combstruct grammars.

Formula

G.f.: 1 - x/g(x) where g(x) is the g.f. of A052818. - Andrew Howroyd, Aug 10 2020

Maple

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

Prog

(PARI) \\ CIK (necklace, indistinct, unlabeled) in Transforms (2).
CIK(p, n)={sum(d=1, n, eulerphi(d)/d*log(subst(1/(1+O(x*x^(n\d))-p), x, x^d)))}
seq(n)={my(p=O(x)); for(n=1, n, p=CIK(x/(1-p), n)); Vec(p, -(n+1))} \\ Andrew Howroyd, Aug 10 2020

Crossrefs

Cf. A052818.

Sequence in context: A147771 A052891 A352905 * A195931 A350906 A082789

Adjacent sequences: A052812 A052813 A052814 * A052816 A052817 A052818

Keyword

easy,nonn

Author

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

Extensions

Terms a(21) and beyond from Andrew Howroyd, Aug 10 2020

Status

approved