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 A236355 #12 Feb 16 2025 08:33:21
%S A236355 28,224,234,496,6200,8128,174592,544635,2886100,33550336
%N A236355 Terms of A050973 that give maximum record values for A050973(k)/A050972(k).
%C A236355 The corresponding terms in A050972 are: 6, 40, 12, 6, 30, 6, 40, 6, ...
%C A236355 Note the subsequence 28, 496, 8128, 33550336: friends of 6 (cf A000396).
%H A236355 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/FriendlyPair.html">Friendly Pair</a>.
%e A236355 28/6 < 224/40 < 234/12 < 496/6 < 6200/30 < 8128/6 < 174592/40 < ....
%o A236355 (PARI) isrmax(i, rmax) = {si = sigma(i); if (gcd(si, i) == 1, return (0)); s = si/i; for (j=1, i\rmax, if ((sigma(j)/j) == s, if ((newr = i/j) > rmax, return (newr)););); return (0);}
%o A236355 lista(nn) = {rmax = 1; for (i = 1, nn, if ((newr = isrmax(i, rmax)), rmax = newr; print1(i, ", ");););}
%Y A236355 Cf. A050972, A050973, A236372.
%K A236355 nonn,more
%O A236355 1,1
%A A236355 _Michel Marcus_, Jan 23 2014