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A055701
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Numbers n such that n | Sigma_7(n) - Phi(n)^7.
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0
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1, 2, 10, 12, 26, 42, 172, 456, 588, 1326, 3315, 3635, 6468, 6720, 12102, 12922, 15288, 17836, 18810, 21756, 32984, 36108, 36603, 40572, 41748, 72905, 78120, 137004, 195216, 291060, 295176, 923212, 978014, 989604, 1009800, 1015768, 1069712, 1602692, 1711024
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OFFSET
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1,2
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COMMENTS
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sigma_7(n) is the sum of the 7th powers of the divisors of n (A013955).
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LINKS
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MATHEMATICA
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Do[If[Mod[DivisorSigma[7, n]-EulerPhi[n]^7, n]==0, Print[n]], {n, 1, 10^5}]
Select[Range[2*10^6], Divisible[DivisorSigma[7, #]-EulerPhi[#]^7, #]&] (* Harvey P. Dale, Dec 02 2016 *)
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PROG
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(PARI) isok(n) = !((sigma(n, 7) - eulerphi(n)^7) % n); \\ Michel Marcus, Mar 02 2014
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Definition corrected and more terms from Michel Marcus, Mar 02 2014
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STATUS
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approved
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