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 A336565 #14 Aug 06 2020 22:04:40
%S A336565 6,28,234,496,588,600,1521,1638,6552,8128,55860,89376,33550336,
%T A336565 168836850
%N A336565 Numbers k for which (A057723(k)-k) is equal to gcd(k-A308135(k), A057723(k)-k).
%C A336565 Numbers k for which A336563(k) = A336566(n) [= gcd(A336563(n), A336564(n))].
%C A336565 Numbers k such that either both A336563(k) and A336564(k) are zero (in which case k is squarefree), or A336563(k) divides A336564(k), in which case k is not squarefree.
%C A336565 Also numbers k for which A336647(n) = 2*n - A057723(n).
%C A336565 Question: Are there any other odd terms apart from 1521 = 39^2 ?
%H A336565 <a href="/index/O#opnseqs">Index entries for sequences where odd perfect numbers must occur, if they exist at all</a>
%o A336565 (PARI)
%o A336565 A007947(n) = factorback(factorint(n)[, 1]);
%o A336565 A057723(n) = { my(r=A007947(n)); (r*sigma(n/r)); };
%o A336565 isA336565(n) = { my(b=A057723(n), c=(sigma(n)-b), d=(b-n)); (gcd(d,(n-c))==d); };
%Y A336565 Cf. A057723, A308135, A336563, A336564, A336566, A336647.
%Y A336565 Cf. A000396 (a subsequence).
%Y A336565 Cf. also A326145.
%K A336565 nonn,more
%O A336565 1,1
%A A336565 _Antti Karttunen_, Jul 26 2020