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 A248888 #8 Nov 25 2021 11:16:22 %S A248888 1,2,3,4,5,6,8,9,10,12,14,15,16,18,20,24,28,30,36,40,42,48,60,72,84, %T A248888 90,96,120,180 %N A248888 Numbers k such that prime(k) <= 2*sigma(k). %C A248888 Obviously only for n = 1, prime(n) = 2*sigma(n). %C A248888 It is interesting that all terms of the sequence A112587 are in the sequence and this sequence has only two more terms 96 & 180. Hence if phi(n) <= 2*tau(n) then prime(n) <= 2*sigma(n). %t A248888 Select[Range[200], Prime[#] <= 2DivisorSigma[1,#]&] %Y A248888 Cf, A000005, A000010, A000040, A000203. %K A248888 nonn,fini,full %O A248888 1,2 %A A248888 _Farideh Firoozbakht_, Oct 17 2014