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 A065390 #22 Mar 22 2025 04:42:16
%S A065390 1,3,7,12,18,28,31,39,42,56,72,91,96,98,168,195,252,280,312,360,372,
%T A065390 392,546,576,744,840,864,992,1092,1170,1344,1512,1680,1860,1872,2016,
%U A065390 2240,2418,2880,3224,3600,3844,4320,4368,4914,5082,5952,6045,6552,7440
%N A065390 Peak values reached by A062402 at the sites listed in A065389.
%H A065390 Amiram Eldar, <a href="/A065390/b065390.txt">Table of n, a(n) for n = 1..958</a> (terms 1..500 from Harry J. Smith)
%F A065390 a(n) = A062402(A065389(n)). - _Amiram Eldar_, Mar 22 2025
%t A065390 a=0; s=0; Do[s=DivisorSigma[1, EulerPhi[n]]; If[s>a, a=s; Print[s]], {n, 1, 10000}]
%t A065390 (* Second program: *)
%t A065390 Union@ FoldList[Max, Array[DivisorSigma[1, EulerPhi[#]] &, 2200]] (* _Michael De Vlieger_, Jun 19 2018 *)
%o A065390 (PARI) { n=r=0; for (m=1, 10^9, x=sigma(eulerphi(m)); if (x > r, r=x; write("b065390.txt", n++, " ", x); if (n==500, return)) ) } \\ _Harry J. Smith_, Oct 18 2009
%Y A065390 Cf. A062402, A000203, A000010, A065389, A065391, A065392, A065393, A065394.
%K A065390 nonn
%O A065390 1,2
%A A065390 _Labos Elemer_, Nov 05 2001