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 A331033 #12 Jan 09 2020 11:54:38 %S A331033 1,30,3,32,5,864,7,128,9,10,11,96,13,3570,45,256,17,216,19,40,147,22, %T A331033 23,6912,25,468,567,224,29,2520,31,416,33,374,35,147456,37,152,117, %U A331033 10800,41,102816,43,88,135,46,47,768,49,21000,153,52,53,6696,165,896,171,7424,59,36960 %N A331033 a(n) is the least k such that the denominator(sigma(sigma(k))/k) equals n. %C A331033 a(n) is the least k such that the A318060(k) equals n. %C A331033 a(n) is divisible by n. %H A331033 Ray Chandler, <a href="/A331033/b331033.txt">Table of n, a(n) for n = 1..10000</a> %o A331033 (PARI) a(n) = my(k=n); while (denominator(sigma(sigma(k))/k) != n, k+=n); k; %Y A331033 Cf. A000203 (sigma), A051027 (sigma(sigma)), A318060. %Y A331033 Cf. A019278, A330598, A331019. %K A331033 nonn %O A331033 1,2 %A A331033 _Michel Marcus_, Jan 08 2020