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 A065270 #6 May 01 2014 02:42:46 %S A065270 1,5,2,9,11,3,4,17,19,21,23,6,10,7,8,33,35,37,39,41,43,45,47,12,22,13, %T A065270 20,14,18,15,16,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95,24,46, %U A065270 25,44,26,42,27,40,28,38,29,36,30,34,31,32,129,131,133,135,137,139,141 %N A065270 Inverse permutation to A065269. %H A065270 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %K A065270 nonn %O A065270 1,2 %A A065270 _Antti Karttunen_, Oct 28 2001