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%I A052815 #13 Aug 10 2020 22:21:52
%S A052815 0,1,2,5,16,56,221,900,3839,16752,74701,338327,1553181,7208191,
%T A052815 33768389,159463655,758291989,3627890869,17450572584,84342086908,
%U A052815 409394388458,1994883122360,9754673396640,47850963112328,235413886888082,1161267995487057,5742484341773444
%N A052815 Number of objects generated by the Combstruct grammar defined in the Maple program. See the link for the grammar specification.
%H A052815 Andrew Howroyd, <a href="/A052815/b052815.txt">Table of n, a(n) for n = 0..200</a>
%H A052815 C. G. Bower, <a href="/transforms2.html">Transforms (2)</a>.
%H A052815 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=780">Encyclopedia of Combinatorial Structures 780</a>
%H A052815 Maplesoft, <a href="https://www.maplesoft.com/support/help/Maple/view.aspx?path=examples%2fcombstruct_grammars">Combstruct grammars</a>.
%F A052815 G.f.: 1 - x/g(x) where g(x) is the g.f. of A052818. - _Andrew Howroyd_, Aug 10 2020
%p A052815 spec := [S,{B=Prod(C,Z),C=Sequence(S),S=Cycle(B)},unlabeled]: seq(combstruct[count](spec,size=n), n=0..20);
%o A052815 (PARI) \\ CIK (necklace, indistinct, unlabeled) in Transforms (2).
%o A052815 CIK(p,n)={sum(d=1, n, eulerphi(d)/d*log(subst(1/(1+O(x*x^(n\d))-p), x, x^d)))}
%o A052815 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
%Y A052815 Cf. A052818.
%K A052815 easy,nonn
%O A052815 0,3
%A A052815 encyclopedia(AT)pommard.inria.fr, Jan 25 2000
%E A052815 Terms a(21) and beyond from _Andrew Howroyd_, Aug 10 2020

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