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 A090538 #4 Dec 05 2013 19:56:38 %S A090538 1,1,1,0,1,4,0,2,1,0,1,7,0,14,0,0,7,2,0,2,20,0,6,1,0,0,25,0,2,3,0,0, %T A090538 12,0,3,24,0,22,2,0,0,14,0,17,32,0,29,6,0,16,19,0,7,9,0,33,19,0,31,3, %U A090538 0,26,4,0,61,31,0,0,45,0,5,29,0,5,63,0,20,39,0,9,40,0,71,1,0,4,25,0,6,4,0,41 %N A090538 Location of 3 in A090537, or 0 if A090537 is 0. %C A090538 a(3n+1) = 0. %Y A090538 Cf. A090535, A090536, A090537. %K A090538 base,nonn %O A090538 1,6 %A A090538 _Amarnath Murthy_, Dec 08 2003 %E A090538 More terms from _David Wasserman_, Jan 03 2006