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 A227303 #26 Oct 14 2023 00:07:09
%S A227303 1,2,4,28,40,78,90,224,360,496,546,2016,2184,8128,10080,10920,11880,
%T A227303 66528,145236,174592,714240,726180,1571328,4333056,6168960,7856640,
%U A227303 12065760,15177600,33550336,47663616,69521760,80196480,91963648,99993600,156854880,459818240,492101632
%N A227303 Numbers k such that k divides sigma(3*k).
%C A227303 If k belongs to the sequence, then sigma(3*k)/k is an integer, so sigma(3*k)/(3*k) is either an integer or a third of an integer, so 3*k is either multiperfect or belongs to A160320 or A160321. - _Michel Marcus_, Jul 09 2013
%H A227303 Jud McCranie, <a href="/A227303/b227303.txt">Table of n, a(n) for n = 1..65</a>
%t A227303 k = 0; lst = {}; While[k < 10^11, If[ Mod[ DivisorSigma[1, 3 k], k] == 0, AppendTo[lst, k]]; k++]; lst (* _Robert G. Wilson v_, Mar 07 2021 *)
%o A227303 (PARI) isok(k) = !(sigma(3*k) % k); \\ _Michel Marcus_, Mar 07 2021
%Y A227303 Cf. A000203, A007691, A227302.
%Y A227303 Cf. A160320, A160321.
%K A227303 nonn
%O A227303 1,2
%A A227303 _Alex Ratushnyak_, Jul 05 2013