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 A129612 #6 Mar 31 2012 13:21:14 %S A129612 0,1,3,2,7,8,6,4,5,17,18,20,21,22,16,19,14,9,10,15,11,13,12,45,46,48, %T A129612 49,50,54,55,57,58,59,61,62,63,64,44,47,53,56,60,42,51,37,23,24,38,25, %U A129612 26,27,43,52,39,28,29,41,33,35,36,40,30,34,31,32,129,130,132,133,134 %N A129612 Signature-permutation of a Catalan automorphism, row 251 of A089840. %C A129612 Automorphism *A089863 = SPINE(*A129612). See the definition given in A122203. %H A129612 A. Karttunen, <a href="/A129612/b129612.txt">Table of n, a(n) for n = 0..2055</a> %H A129612 A. Karttunen, <a href="/A089840/a089840p.txt">Prolog-program which illustrates the construction of this and similar nonrecursive Catalan automorphisms.</a> %H A129612 <a href="/index/Per#IntegerPermutationCatAuto">Index entries for signature-permutations of Catalan automorphisms</a> %o A129612 (Constructive and destructive Scheme implementation of this automorphism. These act on S-expressions, i.e. list-structures:) %o A129612 (define (*A129612 s) (cond ((pair? s) (let ((t (*A089863 s))) (cons (car t) (*A089859 (cdr t))))) (else s))) %o A129612 (define (*A129612! s) (cond ((pair? s) (*A089863! s) (*A089859! (cdr s)))) s) %Y A129612 Inverse: A129611. Differs from A082345 for the first time at n=49, where A082345(49)=27, while a(49)=26. %K A129612 nonn %O A129612 0,3 %A A129612 _Antti Karttunen_, May 22 2007