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 A074687 #6 Oct 15 2015 10:55:23 %S A074687 0,1,3,2,6,7,8,4,5,15,14,16,17,18,19,20,22,13,9,21,10,11,12,39,40,41, %T A074687 37,38,43,42,44,45,46,47,48,49,50,52,51,53,54,55,60,61,62,34,33,63,36, %U A074687 27,23,56,57,64,35,24,58,26,32,29,59,25,28,30,31,113,112,114,115,116 %N A074687 Permutation of natural numbers induced by the Catalan bijection gmA074687! acting on the parenthesizations encoded by A014486/A063171. %H A074687 A. Karttunen, <a href="http://www.iki.fi/~kartturi/matikka/Nekomorphisms/gatomorf.htm">Gatomorphisms</a> (with the complete Scheme source) %H A074687 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A074687 (Scheme function implementing this automorphism on list-structures:) %o A074687 (define (gmA074687! s) (cond ((pair? s) (gmA074687! (car s)) (gmrobl! s) (gmA074687! (cdr s)))) s) %Y A074687 Inverse of A074688 and also a(n) = A057163(A074688(A057163(n))). Cf. A074681-A074690. Occurs in A073200 as row 5572440. %K A074687 nonn %O A074687 0,3 %A A074687 _Antti Karttunen_, Sep 11 2002