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 A030552 #4 Mar 30 2012 18:56:18 %S A030552 3,13,25,30,32,34,36,37,38,40,49,61,77,95,113,121,124,127,130,131,133, %T A030552 136,149,167,185,203,221,229,232,235,238,239,241,244,257,275,282,285, %U A030552 288,291,293,294,297,300,303,306,309,311,312 %N A030552 Position of n-th 3 in A030548. %K A030552 nonn %O A030552 1,1 %A A030552 _Clark Kimberling_