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 A084490 #9 Jul 29 2017 12:44:26 %S A084490 1,2,3,5,4,6,7,8,9,11,10,13,12,14,17,15,16,19,20,18,23,22,21,24,25,26, %T A084490 27,28,29,31,30,32,34,33,35,36,39,37,38,40,42,43,41,44,47,46,45,49,48, %U A084490 50,51,53,52,55,54,58,56,57,59,63,60,61,62,66,64,67,65,71,68,70,69,73 %N A084490 Inverse permutation to A084489. %H A084490 A. Karttunen, <a href="/A084507/a084507.scm.txt">Scheme-program for computing this sequence</a> %H A084490 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %Y A084490 Used to compute A084491. %K A084490 nonn %O A084490 1,2 %A A084490 _Antti Karttunen_, Jun 02 2003