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.
%I A068484 #17 Aug 20 2021 22:49:11 %S A068484 1,2,10,45,65,180,212,222,369,588,810,864,1274,1521,1836,2548,2940, %T A068484 3114,3552,4770,5496,5684,6027,6642,8820,9140,10464,10614,13311,14688, %U A068484 15210,20737,21600,22776,26900,27000,27270,28476,28518,42212,42336 %N A068484 Numbers k that divide phi(k)^2 + sigma(k)^2. %C A068484 a(275) > 7*10^7. - _G. C. Greubel_, Oct 15 2018 %H A068484 G. C. Greubel, <a href="/A068484/b068484.txt">Table of n, a(n) for n = 1..274</a> %p A068484 with(numtheory): select(n->modp(phi(n)^2+sigma(n)^2,n)=0,[$1..42500]); # _Muniru A Asiru_, Oct 16 2018 %t A068484 Select[Range[7000], IntegerQ[(EulerPhi[#]^2 + DivisorSigma[1, #]^2)/#] &] (* _G. C. Greubel_, Oct 15 2018 *) %o A068484 (GAP) Filtered([1..42500],n->(Phi(n)^2+Sigma(n)^2) mod n=0); # _Muniru A Asiru_, Oct 16 2018 %Y A068484 Cf. A072861 (sigma(n)^2), A127473 (phi(n)^2). %K A068484 easy,nonn %O A068484 1,2 %A A068484 _Benoit Cloitre_, Mar 10 2002