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 A123696 #7 Mar 31 2012 13:21:12 %S A123696 0,1,3,2,8,7,4,5,6,21,22,17,18,20,9,10,11,12,13,14,15,16,19,58,59,62, %T A123696 63,64,45,46,48,49,50,54,55,57,61,23,24,25,26,27,28,29,30,31,32,33,34, %U A123696 35,36,37,38,39,40,41,42,43,44,47,51,52,53,56,60,170,171,174,175,176 %N A123696 Signature permutation of a nonrecursive Catalan automorphism: row 1653063 of table A089840. %C A123696 This automorphism is illustrated below, where letters A, B and C refer to arbitrary subtrees located on those nodes and () stands for an implied terminal node. %C A123696 ............................B...C.......C...D.............................. %C A123696 .............................\./.........\./............................... %C A123696 .A...B.............B...C......x...D....B..x............()...C......C..()... %C A123696 ..\./...............\./........\./......\./.............\./.........\./.... %C A123696 ...x...C..-->....A...x......()..x...-->..x..().......()..x....-->....x..(). %C A123696 ....\./...........\./........\./..........\./.........\./.............\./.. %C A123696 .....x.............x..........x............x...........x...............x... %C A123696 See the comments at A123695. %H A123696 A. Karttunen, <a href="/A089840/a089840p.txt">Prolog-program which illustrates the construction of this and other similar nonrecursive Catalan automorphisms.</a> %H A123696 <a href="/index/Per#IntegerPermutationCatAuto">Index entries for signature-permutations of Catalan automorphisms</a> %o A123696 (Scheme function, destructive implementation of this automorphism acting on S-expressions:) (define (*A123696! s) (cond ((null? s) s) ((pair? (car s)) (*A074680! s)) ((pair? (cdr s)) (*A074680! (cdr s)) (*A069770! s))) s) %Y A123696 Inverse: A123695. Row 1653063 of A089840. Variant of A074680. %K A123696 nonn %O A123696 0,3 %A A123696 _Antti Karttunen_, Oct 11 2006