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 A321023 #21 Oct 29 2018 03:29:51 %S A321023 26,62,20840574,25741470,60765690,102435795,277471467,361466454, %T A321023 464465910,1110512403,1927430490,2741174163,3631266639,3844534602, %U A321023 3982743750,4565968407,4612184562,4829319495,4981969978,7066794735,13484870399,14268004443,14550390855,15051147111 %N A321023 Numbers k such that sigma(k) = sigma(k + 15). %H A321023 Giovanni Resta, <a href="/A321023/b321023.txt">Table of n, a(n) for n = 1..116</a> (terms < 2.5*10^12) %e A321023 sigma(26) = sigma(41) = 42, sigma(62) = sigma(77) = 96. %o A321023 (PARI) my(V=vector(15)); for(n=1, 2^28, my(s=sigma(n), r=(n%15)+1); if (s==V[r], print1(n-15, ", ")); V[r]=s) %Y A321023 Cf. A002961, A007373, A015861, A015863, A015865, A015866, A015867, A015876, A015877, A015880, A015881, A015882, A015883, A172335, A181647, A172333. %K A321023 nonn %O A321023 1,1 %A A321023 _Tomohiro Yamada_, Oct 26 2018 %E A321023 a(7)-a(9) from _Amiram Eldar_, Oct 26 2018 %E A321023 a(10)-a(24) from _Giovanni Resta_, Oct 26 2018