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 A113219 #6 Mar 30 2012 18:50:53 %S A113219 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,22,20,24,18,26,19,29,21, %T A113219 27,23,28,25,30,31,32,33,42,35,44,38,47,40,49,34,43,36,45,37,46,39,48, %U A113219 41,62,51,65,53,67,56,69,58,59,60,61,50,63,52,64,54,83,55,85,57,87,71,89 %N A113219 A113218(A113218(n)). %C A113219 Inverse integer permutation of A113221; %C A113219 A113220(a(n)) = a(A113220(n)) = A113218(n). %H A113219 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %K A113219 nonn %O A113219 0,3 %A A113219 _Reinhard Zumkeller_, Oct 18 2005