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A052815
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Number of objects generated by the Combstruct grammar defined in the Maple program. See the link for the grammar specification.
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2
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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
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OFFSET
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0,3
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LINKS
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FORMULA
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MAPLE
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spec := [S, {B=Prod(C, Z), C=Sequence(S), S=Cycle(B)}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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PROG
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(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
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
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STATUS
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approved
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