A052818 Number of objects generated by the Combstruct grammar defined in the Maple program. See the link for the grammar specification.

0, 1, 1, 3, 10, 37, 144, 593, 2515, 10975, 48847, 221071, 1013886, 4702530, 22017327, 103925505, 494000139, 2362666375, 11361442399, 54898445359, 266417109839, 1297935216161, 6345598010686, 31123068382020, 153095423135329, 755103728856195, 3733557839325332

Offset

0,4

Links

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

C. G. Bower, Transforms (2).

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 783

Maplesoft, Combstruct grammars.

Formula

G.f.: x/(1-g(x)) where g(x) is the g.f. of A052815. - Andrew Howroyd, Aug 10 2020

Maple

spec := [S, {C=Sequence(B), B=Cycle(S), S=Prod(C, Z)}, 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=x/(1-CIK(p, n))); Vec(p, -(n+1))}

Crossrefs

Cf. A052815.

Sequence in context: A151053 A151054 A052893 * A299501 A226434 A151055

Adjacent sequences: A052815 A052816 A052817 * A052819 A052820 A052821

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