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 A337382 #7 Aug 27 2020 17:08:42 %S A337382 1,2,3,4,5,7,10,11,13,17,19,22,23,25,26,29,31,33,34,37,38,39,41,43,46, %T A337382 47,51,53,55,57,58,59,61,62,65,67,69,71,73,74,77,79,82,83,85,86,87,89, %U A337382 91,93,94,95,97,101,103,106,107,109,111,113,115,116,118,119,121,122,123,127,129,131,133,134,137,139,141 %N A337382 Numbers k for which A003973(k) < 2*sigma(k). %H A337382 Antti Karttunen, <a href="/A337382/b337382.txt">Table of n, a(n) for n = 1..20000</a> %H A337382 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a> %H A337382 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a> %o A337382 (PARI) %o A337382 A003973(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); sigma(factorback(f)); }; %o A337382 isA337382(n) = (A003973(n)<2*sigma(n)); %Y A337382 Cf. A000203, A003961, A003973. %Y A337382 Cf. A337381 (complement). %Y A337382 Positions of zeros in A337383. %Y A337382 Subsequence of A337379. %Y A337382 Cf. also A246281. %K A337382 nonn %O A337382 1,2 %A A337382 _Antti Karttunen_, Aug 27 2020