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 A030491 #4 Mar 30 2012 18:56:18 %S A030491 27,30,35,38,41,45,51,54,59,62,65,69,75,78,83,86,89,93,96,100,104,108, %T A030491 112,116,123,129,132,137,144,148,153,159,162,167,174,178,181,186,191, %U A030491 196,201,206,214,218,224,228,232,237,243,249 %N A030491 Position of n-th 4 in A030298. %K A030491 nonn %O A030491 1,1 %A A030491 _Clark Kimberling_