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A322656
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Denominator of (Sum_{d|n} sigma(d)) / sigma(n).
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3
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1, 3, 4, 7, 6, 3, 8, 15, 13, 9, 12, 28, 14, 2, 24, 31, 18, 13, 20, 6, 32, 9, 24, 6, 31, 7, 20, 56, 30, 18, 32, 21, 48, 27, 16, 91, 38, 5, 56, 45, 42, 8, 44, 84, 13, 18, 48, 124, 19, 93, 72, 98, 54, 15, 72, 20, 16, 45, 60, 24, 62, 8, 52, 127, 4, 36, 68, 126, 96
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OFFSET
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1,2
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COMMENTS
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Also denominator of Sum_{d|n} (sigma(d) / sigma(n)).
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LINKS
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FORMULA
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EXAMPLE
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For n = 4; a(4) = denominator((Sum_{d|4} sigma(d)) / sigma(4)) = denominator((1 + 3 + 7) / (1 + 2 + 4)) = denominator(11/7) = 7.
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MATHEMATICA
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Table[Denominator[Sum[DivisorSigma[1, d], {d, Divisors[n]}] / DivisorSigma[1, n]], {n, 1, 100}] (* Vaclav Kotesovec, Dec 22 2018 *)
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PROG
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(Magma) [Denominator(&+[SumOfDivisors(d): d in Divisors(n)] / SumOfDivisors(n)): n in [1..1000]]
(PARI) a(n) = denominator(sumdiv(n, d, sigma(d))/sigma(n)); \\ Michel Marcus, Dec 22 2018
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CROSSREFS
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KEYWORD
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nonn,frac
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AUTHOR
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STATUS
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approved
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