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A032201
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Number of rooted compound windmills with n nodes and leaves of 2 colors.
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2
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2, 2, 5, 13, 40, 128, 457, 1660, 6308, 24409, 96363, 385535, 1561706, 6387135, 26347199, 109471366, 457758461, 1924845582, 8134171456, 34526723986, 147139513066, 629314845284, 2700401538933, 11622130671430
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OFFSET
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1,1
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LINKS
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FORMULA
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Shifts left under "CIK" (necklace, indistinct, unlabeled) transform.
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PROG
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(PARI)
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(1)); for(i=1, n, p=2+CIK(x*p, i)); Vec(p)} \\ Andrew Howroyd, Jun 20 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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