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 A063788 #15 May 28 2025 00:56:54 %S A063788 18,88,4030,5830,518656,13174976,134094848,2146926592, %T A063788 2251798907715584,12504224434300196,324257317741920256 %N A063788 Numbers k such that sigma(k) = 2k + Omega(k), where Omega(n) is the number of prime divisors of n (with repetition). %C A063788 Includes terms 633825300114085990300727115776 and 2596148429267411760623818083663872. - _Donovan Johnson_, Dec 19 2008; edited by _Max Alekseyev_, May 27 2025 %C A063788 Terms a(2)-a(4) come from A088832, a(5) from A223609, a(6) and a(10) from A088833, a(7) from A141546, a(8) from A141547, a(9) from A275701, a(11) from A223611. Also includes the following terms k with Omega(k) = 56: 246434407522188377975875310632234056969345758857269346304, 15937923506379504700185810932457673797717574263217988829184, 264936582814027097239593278653623212574863771975442952634761216, 7948097484419456643668355219907727481405487440330234556835692544. - _Max Alekseyev_, May 27 2025 %F A063788 Numbers k such that A000203(k) = 2k + A001222(k). - _Wesley Ivan Hurt_, Oct 30 2022 %o A063788 (PARI) for(n=1,10^8, if(sigma(n)==2*n+bigomega(n),print(n))) %Y A063788 Cf. A000203 (sigma), A001222 (Omega), A088832, A223609, A088833, A141546, A141547, A275701, A223611. %K A063788 more,nonn %O A063788 1,1 %A A063788 _Jason Earls_, Aug 16 2001 %E A063788 a(7)-a(8) from _Donovan Johnson_, Dec 19 2008 %E A063788 a(9) from _Donovan Johnson_ confirmed and a(10)-a(11) added by _Max Alekseyev_, May 27 2025