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 A358768 #4 Dec 19 2022 15:07:13 %S A358768 2,4,6,7,9,10,11,12,16,17,19,20,21,25,26,29,30,31,32,33,35,41,43,45, %T A358768 46,47,48,51,52,54,55,56,57,60,64,67,71,72,74,75,78,79,80,85,87,88,91, %U A358768 92,93,95,96,97,98,101,105,106,107,108,109,113,117,118,122,123,126,127,128,129,130,136,137,138 %N A358768 Numbers k with an odd number of prime factors (when counted with multiplicity) in sigma(k), the sum of divisors of k. %H A358768 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a> %o A358768 (PARI) isA358768(n) = (bigomega(sigma(n))%2); %Y A358768 Positions of odd terms in A058063. Positions of -1's in A358766. %Y A358768 Cf. A000203, A001222, A358767 (complement). %K A358768 nonn %O A358768 1,1 %A A358768 _Antti Karttunen_, Dec 19 2022