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 A065392 #28 Mar 22 2025 04:41:34
%S A065392 1,2,6,8,12,30,36,72,126,180,360,432,660,930,1512,2160,3300,3780,5184,
%T A065392 6552,11160,13860,19800,23232,32760,45360,47520,50400,58080,61776,
%U A065392 102300,110160,137592,155520,163296,196560,212960,252000,272160,284580
%N A065392 a(n) = A062401(A065391(n)): phi(sigma(m)) peak values for numbers m (listed in A065391) at which those peaks are first reached.
%H A065392 Amiram Eldar, <a href="/A065392/b065392.txt">Table of n, a(n) for n = 1..249</a> (terms 1..100 from Harry J. Smith)
%t A065392 With[{s = Array[EulerPhi@ DivisorSigma[1, #] &, 10^5]}, Union@ FoldList[Max, s] ] (* _Michael De Vlieger_, Dec 06 2018 *)
%o A065392 (PARI) { n=r=0; for (m=1, 10^9, x=eulerphi(sigma(m)); if (x > r, r=x; write("b065392.txt", n++, " ", x); if (n==100, return)) ) } \\ _Harry J. Smith_, Oct 18 2009
%Y A065392 Cf. A000010, A000203, A062401, A065389, A065390, A065391, A065393, A065394.
%K A065392 nonn
%O A065392 1,2
%A A065392 _Labos Elemer_, Nov 14 2001