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 A030609 #4 Mar 30 2012 18:56:19 %S A030609 12,19,27,31,33,34,46,47,61,71,73,78,79,92,96,105,115,116,127,128,131, %T A030609 132,137,138,140,141,152,165,168,185,186,188,195,196,198,211,213,224, %U A030609 229,231,234,243,244,252,254,264,271,273,286 %N A030609 Position of n-th 4 in A030604. %K A030609 nonn %O A030609 1,1 %A A030609 _Clark Kimberling_