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 A124141 #25 Dec 20 2024 02:38:43
%S A124141 38,92,153,284,332,459,494,885,956,1035,1358,1784,2295,2528,2678,5434,
%T A124141 5607,6027,6255,7564,7928,8235,8648,9729,10325,10413,12008,14104,
%U A124141 15813,16198,17794,22712,22936,23247,27082,27626,28917,30938,33082,34688,37790,37816
%N A124141 Numbers k such that there is a number m < k satisfying A000203(k) = A000203(m) = m + k - gcd(m,k).
%H A124141 Amiram Eldar, <a href="/A124141/b124141.txt">Table of n, a(n) for n = 1..360</a>
%H A124141 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).
%e A124141 38 is in the sequence because A000203(24) = A000203(38) = 60 = 24 + 38 - gcd(24,38).
%o A124141 (PARI) isok(k) = {my(sk = sigma(k)); for (m=1, k, if ((sk == sigma(m)) && (sk == m + k - gcd(m,k)), return (1));); return (0);} \\ _Michel Marcus_, Oct 27 2019
%o A124141 (PARI) is(k) = {my(s = sigma(k), v = invsigma(s)); for(i = 1, #v, if(v[i] < k && s == v[i] + k - gcd(v[i], k), return(1))); 0;} \\ _Amiram Eldar_, Dec 20 2024, using _Max Alekseyev_'s invphi.gp
%Y A124141 Cf. A000203, A124140.
%Y A124141 Subsequence of A069822.
%K A124141 nonn
%O A124141 1,1
%A A124141 _Yasutoshi Kohmoto_, Dec 01 2006
%E A124141 Edited by _Stefan Steinerberger_, Aug 14 2007
%E A124141 More terms from _Jinyuan Wang_, Feb 07 2022