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 A030571 #4 Mar 30 2012 18:56:18 %S A030571 3,12,24,31,33,35,36,37,39,41,48,60,75,93,111,121,124,127,129,130,133, %T A030571 136,147,165,183,201,219,229,232,235,237,238,241,244,255,273,284,287, %U A030571 290,291,293,296,299,302,305,308,309,311,314 %N A030571 Position of n-th 3 in A030567. %K A030571 nonn %O A030571 1,1 %A A030571 _Clark Kimberling_