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A099740
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a(n) = Sum_{k|n} k!*mu(k), where mu() is the Moebius function.
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2
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1, -1, -5, -1, -119, 713, -5039, -1, -5, 3628679, -39916799, 713, -6227020799, 87178286159, 1307674367875, -1, -355687428095999, 713, -121645100408831999, 3628679, 51090942171709434955, 1124000727777567763199, -25852016738884976639999, 713, -119, 403291461126605629356979199
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OFFSET
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1,3
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COMMENTS
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a(2^k)=1, a(3^k)=5, a(5^k)=119, a(6*2^i*3^j)=713, a(7^k)=5039, a(10*2^i*5^j)=3628679, etc. - Robert G. Wilson v, Nov 12 2004
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LINKS
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FORMULA
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MATHEMATICA
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f[n_] := Block[{k = Divisors[n]}, Plus @@ (k!MoebiusMu[k])]; Table[ f[n], {n, 25}] (* Robert G. Wilson v, Nov 12 2004 *)
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PROG
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(PARI) a(n) = sumdiv(n, d, d!*moebius(d)); \\ Michel Marcus, Feb 19 2017
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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