cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A055698 Numbers n such that n | (sigma_4(n) + phi(n)^4).

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%I A055698 #13 Mar 17 2020 12:11:25
%S A055698 1,2,6,13588,48238,54490,69004,194460,353228,577980,638652,1478962,
%T A055698 1882188,2190515,2677740,3404598,3875508,8456460,9978863,16320458,
%U A055698 41199780,45112860,76132715,236405988,357846865,682983756,689274612,733141332,1185444052,1752193128
%N A055698 Numbers n such that n | (sigma_4(n) + phi(n)^4).
%C A055698 Sigma_4(n) is the sum of the 4th powers of the divisors of n (A001159).
%t A055698 Do[If[Mod[DivisorSigma[4, n] + EulerPhi[n]^4, n]==0, Print[n]], {n, 1, 10^6}]
%o A055698 (PARI) isok(k) = (sigma(k, 4) + eulerphi(k)^4)%k == 0; \\ _Jinyuan Wang_, Mar 17 2020
%Y A055698 Cf. A001159.
%K A055698 nonn
%O A055698 1,2
%A A055698 _Robert G. Wilson v_, Jun 09 2000
%E A055698 More terms from _Robert G. Wilson v_, Mar 11 2013
%E A055698 More terms from _Jinyuan Wang_, Mar 17 2020