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 A337198 #9 Aug 20 2020 21:24:54 %S A337198 1,1,1,1,1,1,1,1,2,2,1,1,1,1,1,1,2,2,2,2,1,2,1,1,1,2,2,1,1,2,1,1,1,2, %T A337198 1,2,2,1,1,2,2,1,2,2,2,2,1,1,2,2,2,2,2,1,2,1,2,2,1,2,1,1,2,1,2,2,2,1, %U A337198 1,2,2,2,2,2,1,2,1,2,2,2,2,1,2,1,2,2,1,2,2,2,1,2,1,2,1,1,2,2,2,2,2,2,2,2,1 %N A337198 Number of distinct prime factors in A337194(n) = 1+A000265(sigma(n)), where A000265(k) gives the odd part of k. %C A337198 The first 3 occurs at a(137). %H A337198 Antti Karttunen, <a href="/A337198/b337198.txt">Table of n, a(n) for n = 1..65537</a> %H A337198 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a> %F A337198 a(n) = A001221(A337194(n)) = 1 + A001221(A336698(n)). %o A337198 (PARI) %o A337198 A000265(n) = (n>>valuation(n,2)); %o A337198 A337198(n) = (omega(1+A000265(sigma(n)))); %Y A337198 Cf. A000203, A000265, A001221, A161942, A336698, A337194. %Y A337198 Cf. also A058062, A336691, A337199. %K A337198 nonn %O A337198 1,9 %A A337198 _Antti Karttunen_, Aug 20 2020