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 A089843 #10 Mar 31 2012 14:02:29 %S A089843 0,1,2,3,6,5,4,7,8,11,10,9,17,18,19,21,20,12,13,14,16,15,22,23,26,25, %T A089843 24,27,28,35,44,43,36,33,40,29,32,37,42,39,34,41,38,31,30,45,46,49,48, %U A089843 47,50,51,58,67,66,59,56,63,52,55,60,65,62,57,64,61,54,53,68,69,72,71 %N A089843 Involution of natural numbers which shows the position of the inverse of each non-recursive Catalan automorphism in table A089840. %H A089843 A. Karttunen, <a href="/A089839/a089839.c.txt">C-program for computing the initial terms of this sequence</a> %H A089843 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %Y A089843 Cf. A089837, A089838. %K A089843 nonn %O A089843 0,3 %A A089843 _Antti Karttunen_, Dec 05 2003