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 A332208 #20 Feb 09 2021 01:55:48
%S A332208 6,28,120,135,270,496,672,891,1080,1638,1782,3780,8128,18600,20580,
%T A332208 24948,26208,30240,32640,32760,35640,41850,44226,55860,66960,164640,
%U A332208 167400,185220,199584,200655,273000,293760,307125,401310,441936,446880,502740,523776,544635,614250,707616,802620,819000,884520
%N A332208 Numbers k such that the squarefree kernel of sigma(k) is equal to the squarefree kernel of 2*k.
%C A332208 Numbers k such that sigma(k) has the same set of distinct prime factors as 2*k.
%C A332208 Numbers k such that A007947(sigma(k)) is equal to A007947(2*k), or equally, that A087207(sigma(k)) is equal to A087207(2*k).
%C A332208 Of the first 256 terms 44 are odd, and none occurs in A228058. Compare also to A331752.
%H A332208 Antti Karttunen, <a href="/A332208/b332208.txt">Table of n, a(n) for n = 1..256</a>
%H A332208 <a href="/index/O#opnseqs">Index entries for sequences where any odd perfect numbers must occur</a>
%F A332208 {n: A080398(n) == A007947(2n)}.
%t A332208 Select[Range[10^6], SameQ @@ Map[Times @@ FactorInteger[#][[All, 1]] &, {DivisorSigma[1, #], 2 #}] &] (* _Michael De Vlieger_, Feb 08 2020 *)
%o A332208 (PARI)
%o A332208 A007947(n) = factorback(factorint(n)[, 1]);
%o A332208 isA332208(n) = (A007947(sigma(n)) == A007947(2*n));
%Y A332208 Cf. A000203, A007947, A080398, A087207, A228058, A331751, A331752.
%Y A332208 Subsequences: A000396, A027687.
%K A332208 nonn
%O A332208 1,1
%A A332208 _Antti Karttunen_, Feb 07 2020