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 A213638 #4 Jul 03 2012 15:38:44 %S A213638 2,6,8,12,14,18,20,26,30,32,38,42,44,50,54,56,62,66,68,72,74,78,80,86, %T A213638 90,92,98,102,104,110,114,116,122,126,128,132,134,138,140,146,150,152, %U A213638 158,162,164,170,174,176,182,186,188,192,194,198,200,206,210 %N A213638 Positions of 2 in A213636. %C A213638 (See A213636.) %t A213638 (See A213636.) %Y A213638 Cf. A213636, A213637. %K A213638 nonn,easy %O A213638 1,1 %A A213638 _Clark Kimberling_, Jun 16 2012