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 A190687 #4 Mar 30 2012 18:57:28 %S A190687 4,8,12,15,19,23,27,30,34,38,45,49,53,56,60,64,68,71,75,79,83,86,90, %T A190687 94,101,105,109,112,116,120,124,127,131,135,142,146,150,157,161,165, %U A190687 168,172,176,180,183,187,191,198,202,206,209,213,217,221,224,228,232,236,239,243,247,254,258,262,265,269,273,277,280,284,288,292 %N A190687 Positions of 3 in A190683. %C A190687 See A190683. %t A190687 (See A190683.) %Y A190687 Cf. A190683. %K A190687 nonn %O A190687 1,1 %A A190687 _Clark Kimberling_, May 17 2011