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A289412
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a(n) = denominator of (sigma(n) / phi(n)).
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6
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1, 1, 1, 2, 2, 1, 3, 4, 6, 2, 5, 1, 6, 1, 1, 8, 8, 2, 9, 4, 3, 5, 11, 2, 20, 2, 9, 3, 14, 1, 15, 16, 5, 8, 1, 12, 18, 3, 3, 8, 20, 1, 21, 5, 4, 11, 23, 4, 14, 20, 4, 12, 26, 3, 5, 1, 9, 14, 29, 2, 30, 5, 9, 32, 4, 5, 33, 16, 11, 1, 35, 8, 36, 6, 10, 9, 5, 1
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OFFSET
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1,4
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COMMENTS
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a(n) = 1 for numbers in A020492 (balanced numbers).
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LINKS
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FORMULA
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EXAMPLE
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For n = 7, sigma(7) / phi(7) = 8/6 = 4/3, a(n) = 3.
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MATHEMATICA
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Array[Denominator[DivisorSigma[1, #]/EulerPhi[#]] &, 78] (* Michael De Vlieger, Aug 19 2017 *)
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PROG
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(Magma) [Denominator(SumOfDivisors(n) / EulerPhi(n)): n in[1..1000]]
(PARI) a(n) = denominator(sigma(n)/eulerphi(n)); \\ Michel Marcus, Aug 21 2017
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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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