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 A336397 #19 Jul 24 2020 10:57:57 %S A336397 1,6,753480,429520946400 %N A336397 Numbers k such that both k and A122111(k) [its conjugated prime factorization] are Ore's Harmonic numbers (A001599). %C A336397 The initial four terms were found from the b-file of 937 terms provided in A001599. %C A336397 There also at least these additional terms present: 439151400324000, 889013810412000, 106713790278732000, that were found from the file of conjectured initial 10000 terms of A001599 provided by _David A. Corneth_ under that entry. However, there might be further terms in the range between. %C A336397 Note that A122111(889013810412000) = 106713790278732000, and vice versa, which proves that the intersection of A001599 and A088902 (equal to the intersection of A088902 with A336317) is not equal to this sequence, but just a proper subsequence. %o A336397 (PARI) %o A336397 isA001599(n) = !((sigma(n,0)*n)%sigma(n,1)); %o A336397 isA336397(n) = (isA001599(n) && isA001599(A122111(n))); %o A336397 \\ Or alternatively, by using standalone program given in A336317: %o A336397 isA336397(n) = (isA001599(n) && isA336317(n)); %Y A336397 Intersection of A001599 and A336317. %Y A336397 Cf. A088902, A122111. %K A336397 nonn,hard,more %O A336397 1,2 %A A336397 _Antti Karttunen_, Jul 20 2020