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Numbers n such that n | (sigma_4(n) + phi(n)^4).
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%I #13 Mar 17 2020 12:11:25

%S 1,2,6,13588,48238,54490,69004,194460,353228,577980,638652,1478962,

%T 1882188,2190515,2677740,3404598,3875508,8456460,9978863,16320458,

%U 41199780,45112860,76132715,236405988,357846865,682983756,689274612,733141332,1185444052,1752193128

%N Numbers n such that n | (sigma_4(n) + phi(n)^4).

%C Sigma_4(n) is the sum of the 4th powers of the divisors of n (A001159).

%t Do[If[Mod[DivisorSigma[4, n] + EulerPhi[n]^4, n]==0, Print[n]], {n, 1, 10^6}]

%o (PARI) isok(k) = (sigma(k, 4) + eulerphi(k)^4)%k == 0; \\ _Jinyuan Wang_, Mar 17 2020

%Y Cf. A001159.

%K nonn

%O 1,2

%A _Robert G. Wilson v_, Jun 09 2000

%E More terms from _Robert G. Wilson v_, Mar 11 2013

%E More terms from _Jinyuan Wang_, Mar 17 2020