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
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