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 A030553 #4 Mar 30 2012 18:56:18 %S A030553 4,15,27,39,42,44,46,48,50,51,52,63,80,98,116,134,139,142,145,148,151, %T A030553 152,154,170,188,206,224,242,247,250,253,256,259,260,262,278,296,314, %U A030553 332,350,355,358,361,364,367,368,370,386,390 %N A030553 Position of n-th 4 in A030548. %K A030553 nonn %O A030553 1,1 %A A030553 _Clark Kimberling_