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 A072759 #2 Mar 30 2012 18:57:04 %S A072759 0,1,2,3,4,6,5,7,8,10,12,14,9,11,16,13,15,18,20,22,24,17,26,28,30,19, %T A072759 32,21,23,34,25,36,38,27,29,40,31,42,44,33,46,48,50,35,52,54,37,56,39, %U A072759 58,60,62,41,64,66,43,68,45,70,72,47,49,74,51,76,78,53,55,80,82,57,84 %N A072759 Inverse of permutation A072758 of the nonnegative integers. %Y A072759 Cf. A072758. %K A072759 nonn %O A072759 0,3 %A A072759 _Clark Kimberling_, Jul 09 2002