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 A057301 #2 Mar 30 2012 17:38:10 %S A057301 0,1,4,5,2,3,6,7,32,33,36,37,34,35,38,39,8,9,12,13,10,11,14,15,40,41, %T A057301 44,45,42,43,46,47,16,17,20,21,18,19,22,23,48,49,52,53,50,51,54,55,24, %U A057301 25,28,29,26,27,30,31,56,57,60,61,58,59,62,63,512,513,516,517,514,515 %N A057301 Binary counter with bit positions permuted in increasing length cycles: 0;2,1;5,3,4;9,6,7,8,... %C A057301 A permutation of the integers %Y A057301 A057300. %K A057301 easy,nonn %O A057301 0,3 %A A057301 _Marc LeBrun_, Aug 24 2000