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 A113324 #6 Mar 30 2012 18:50:53 %S A113324 1,2,4,3,6,5,8,10,7,12,14,9,16,11,18,20,13,22,15,24,26,17,28,30,19,32, %T A113324 21,34,36,23,38,40,25,42,27,44,46,29,48,31,50,52,33,54,56,35,58,37,60, %U A113324 62,39,64,41,66,68,43,70,72,45,74,47,76,78,49,80,82,51,84,53,86,88,55 %N A113324 Inverse integer permutation of A113321. %C A113324 A113325 = a(a(n)); %C A113324 a(n) = A113321(A113325(n)) = A113325(A113321(n)). %H A113324 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %K A113324 nonn %O A113324 1,2 %A A113324 _Reinhard Zumkeller_, Oct 26 2005