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 A138945 #2 Jul 14 2012 11:32:20 %S A138945 1,9,12,15,17,20,22,24,27,29,31,33,35,37,39,41,43,45,46,48,50,52,54, %T A138945 56,57,59,61,63,64,66,68,69,71,73,75,76,78,80,81,83,85,86,88,89,91,93, %U A138945 94,96,98,99,101,102,104,106,107,109,110,112,113,115,117,118,120,121,123 %N A138945 Positive integers not in A132018. %C A138945 Sequence A132018 was motivated by analogy to A073071. %C A138945 The latter remains quite dense in N: up to 1000 only about every 5th number is missing, which motivated to introduce its complement in N*, A138945. %C A138945 While A132018 starts in a similar way, it becomes more and more sparse (since A000041 grows much faster); and consequently the present sequence becomes very dense. %o A138945 (PARI) pp=1;k=0;for(n=1,999,pp*=numbpart(n);while(k++!<=pp,print1(k"," ))) %Y A138945 Cf. A132018, A137620, A058694, A073071, A138946, A135667. %K A138945 nonn,easy %O A138945 1,2 %A A138945 _M. F. Hasler_, May 04 2008