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 A074690 #6 Oct 15 2015 10:55:23 %S A074690 0,1,3,2,6,7,8,5,4,14,15,16,17,18,19,20,22,11,12,21,13,10,9,37,38,39, %T A074690 40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,60,61,62,28,29,63,30, %U A074690 31,32,56,57,64,33,34,59,36,25,26,58,35,27,24,23,107,108,109,110,111 %N A074690 Permutation of natural numbers induced by the Catalan bijection gmA074690! acting on the parenthesizations encoded by A014486/A063171. %H A074690 A. Karttunen, <a href="http://www.iki.fi/~kartturi/matikka/Nekomorphisms/gatomorf.htm">Gatomorphisms</a> (with the complete Scheme source) %H A074690 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A074690 (Scheme function implementing this automorphism on list-structures:) %o A074690 (define (gmA074690! s) (cond ((pair? s) (gmA074690! (car s)) (gmrobl! s))) s) %Y A074690 Inverse of A074689. a(n) = A057163(A074686(A057163(n))). Cf. A074681-A074688. Occurs in A073200. %K A074690 nonn %O A074690 0,3 %A A074690 _Antti Karttunen_, Sep 11 2002