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A295506
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a(n) = Sum_{d|n} mu(n/d)*5^(d-1).
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5
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1, 4, 24, 120, 624, 3096, 15624, 78000, 390600, 1952496, 9765624, 48824880, 244140624, 1220687496, 6103514976, 30517500000, 152587890624, 762939059400, 3814697265624, 19073484374880, 95367431624976, 476837148437496, 2384185791015624, 11920928906172000
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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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nmax = 20; Rest[CoefficientList[Series[Sum[MoebiusMu[k] * x^k / (1 - 5*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)*5^(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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