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A055701 Numbers n such that n | Sigma_7(n) - Phi(n)^7. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

sigma_7(n) is the sum of the 7th powers of the divisors of n (A013955).

LINKS

Table of n, a(n) for n=1..39.

MATHEMATICA

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 *)

PROG

(PARI) isok(n) = !((sigma(n, 7) - eulerphi(n)^7) % n); \\ Michel Marcus, Mar 02 2014

CROSSREFS

Sequence in context: A022367 A004686 A080139 * A176978 A186630 A154391

Adjacent sequences:  A055698 A055699 A055700 * A055702 A055703 A055704

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jun 09 2000

EXTENSIONS

Definition corrected and more terms from Michel Marcus, Mar 02 2014

STATUS

approved

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Last modified August 25 09:11 EDT 2019. Contains 326323 sequences. (Running on oeis4.)