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 A355707 #26 Jul 18 2022 14:18:02 %S A355707 786432,3500658,41641938,75031250,121773618,175781250,408008178, %T A355707 892531250,1031215698 %N A355707 Nonsquare numbers k such that tau(sigma(tau(k))) = sigma(tau(sigma(k))), where tau is A000005 and sigma is A000203. %C A355707 a(9) > 10^9. %C A355707 From _Jon E. Schoenfield_, Jul 16 2022: (Start) %C A355707 Additional terms < 10^12 (the lists below may not include all such terms): %C A355707 - terms of the form 2*p^6*q^4, where p and q are distinct odd primes: 2610031250, 4984611858, 8745031250, 22102531250, 23178336818, 41404635378, 56789218098, 69194232018, 106837531250, 115908606338, 379290886578, 806279828978, 887445031250; %C A355707 - terms of the form 2*p^10*q^2, where p and q are distinct odd primes: 5644531250, 32832031250, 67988281250, 98457031250, 154707031250, 199238281250, 335175781250, 544707031250, 584550781250. (End) %o A355707 (PARI) isok(k) = !issquare(k) && (numdiv(sigma(numdiv(k))) == sigma(numdiv(sigma(k)))); \\ _Michel Marcus_, Jul 16 2022 %Y A355707 Cf. A000005, A000203, A076361. %Y A355707 Intersection of A000037 and A237613. %K A355707 nonn,more %O A355707 1,1 %A A355707 _Mohammed Yaseen_, Jul 14 2022 %E A355707 a(9) from _Jon E. Schoenfield_, Jul 16 2022