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A295505
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a(n) = Sum_{d|n} mu(n/d)*4^(d-1).
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5
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1, 3, 15, 60, 255, 1005, 4095, 16320, 65520, 261885, 1048575, 4193220, 16777215, 67104765, 268435185, 1073725440, 4294967295, 17179802640, 68719476735, 274877644740, 1099511623665, 4398045462525, 17592186044415, 70368739967040, 281474976710400
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OFFSET
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1,2
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LINKS
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FORMULA
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MATHEMATICA
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Table[Sum[MoebiusMu[n/d]4^(d-1), {d, Divisors[n]}], {n, 30}] (* Harvey P. Dale, Nov 08 2020 *)
nmax = 20; Rest[CoefficientList[Series[Sum[MoebiusMu[k] * x^k / (1 - 4*x^k), {k, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Dec 11 2020 *)
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PROG
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(PARI) {a(n) = sumdiv(n, d, moebius(n/d)*4^(d-1))}
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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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