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 A104773 #3 Mar 30 2012 18:50:49 %S A104773 1,2,15,4,65,42,161,78,185,114,201,310,305,186,365,222,381,610,485, %T A104773 470,545,530,1969,1246,917,402,681,678,1585,1570,1169,830,905,890,921, %U A104773 1510,1293,2954,2321,654,1101,1810,1205,2486,1757,762,4609,2110,1385,834 %N A104773 A104772(A104772(n)). %C A104773 A104774(a(n)) = A104772(n); %C A104773 a(odd) = odd and a(even) = even. %K A104773 nonn %O A104773 1,2 %A A104773 _Reinhard Zumkeller_, Mar 24 2005