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 A118202 #3 Mar 31 2012 13:21:31 %S A118202 0,1,4,2,1715,31,3,5,16,14,12,10,8,6,476,101,99,97,23,303,7,9,11,13, %T A118202 15,17,52,50,48,46,44,42,40,38,36,34,32,30,28,683,681,22,20,18,24,77, %U A118202 699,697,703,695,693,691,689,687,1723,1725,1721,267,269,2686,67,263,19,21 %N A118202 Inverse of A118201, or -1 if n does not occur in A118201. %C A118202 Conjecture that a(n) is never -1. %Y A118202 Cf. A118201, A057167. %K A118202 nonn %O A118202 0,3 %A A118202 _Franklin T. Adams-Watters_, Apr 14 2006