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 A353635 #13 May 04 2022 17:12:57
%S A353635 1,26,74,122,146,314,386,554,626,794,842,914,1082,1226,1322,1346,1466,
%T A353635 1514,1754,1994,2186,2306,2402,2426,2474,2642,2762,2906,3242,3314,
%U A353635 3506,3746,3866,3986,4034,4274,4682,4946,5114,5186,5594,5714,5834,6122,6434,6506,6626,7034,7466,8042,8114,8354,8522,8546,8714,8882
%N A353635 Numbers k such that phi(k) = phi(sigma(k)) and A003958(k) = A003958(sigma(k)).
%C A353635 Question 1: Are there any odd terms after the initial 1?
%C A353635 Interestingly, most of the terms seem to belong to a set where the abundancy index (ratio sigma(n)/n) converges towards 3/2. But there are exceptions, see A353634 for example.
%H A353635 <a href="/index/O#opnseqs">Index entries for sequences where odd perfect numbers must occur, if they exist at all</a>
%H A353635 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%o A353635 (PARI)
%o A353635 A003958(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]--); factorback(f); };
%o A353635 isA353635(n) = { my(s=sigma(n)); ((eulerphi(s)==eulerphi(n)) && (A003958(s)==A003958(n))); };
%Y A353635 Intersection of A006872 and A351446. A353634 lists the nondeficient terms.
%Y A353635 Cf. A000010, A000203, A003958, A062401, A351440, A351442.
%K A353635 nonn
%O A353635 1,2
%A A353635 _Antti Karttunen_, May 04 2022