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A245776
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Numerator of (n/tau(n) - sigma(n)/n).
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5
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0, -1, 1, -5, 13, -1, 33, 1, 14, 7, 97, -1, 141, 25, 43, 101, 253, 5, 321, 37, 313, 85, 481, 1, 532, 127, 569, 8, 781, 27, 897, 323, 299, 235, 1033, 53, 1293, 301, 1297, 11, 1597, 83, 1761, 179, 173, 457, 2113, 133, 2230, 971, 771, 529, 2701, 163, 2737, 34, 2929, 751, 3361, 11, 3597, 865, 1115
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OFFSET
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1,4
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COMMENTS
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See A245777 - denominator of (n/tau(n) - sigma(n)/n).
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LINKS
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FORMULA
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a(n) = 1 for n = 3, 8 and 24.
a(n) < 0 for n = 2, 4, 6 and 12.
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EXAMPLE
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For n = 9; a(9) = numerator(9/tau(9) - sigma(9)/9) = numerator(9/3 - 13/9) = numerator(14/9) = 14.
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MATHEMATICA
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a245776[n_Integer] :=
Map[Numerator[#/DivisorSigma[0, #] - DivisorSigma[1, #]/#] &,
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PROG
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(Magma) [Numerator((n/(#[d: d in Divisors(n)]))-(SumOfDivisors(n)/n)): n in [1..1000]]
(PARI) vector(150, n, numerator(n/numdiv(n) - sigma(n)/n)) \\ Derek Orr, Aug 01 2014
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CROSSREFS
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KEYWORD
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sign,frac
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AUTHOR
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STATUS
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approved
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