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 A130572 #7 Jan 27 2014 16:23:33 %S A130572 0,1,2,3,4,5,6,7,8,9,10,11,13,14,15,16,17,18,19,20,12,21,22,24,25,26, %T A130572 27,28,29,30,23,31,32,33,35,36,37,38,39,40,34,41,42,43,44,46,47,48,49, %U A130572 50,45,51,52,53,54,55,57,58,59,60,56,61,62,63,64,65,66,68,69,70,67,71,72 %N A130572 Inverse permutation to A130571. %C A130572 A130574(n) = a(a(n)); a(A130575(n)) = A130575(n); %H A130572 R. Zumkeller, <a href="/A130572/b130572.txt">Table of n, a(n) for n = 0..10000</a> %H A130572 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %K A130572 nonn,look %O A130572 0,3 %A A130572 _Reinhard Zumkeller_, Jun 05 2007