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 A123495 #7 Mar 31 2012 13:21:12 %S A123495 0,1,3,2,6,7,8,4,5,14,15,16,17,18,21,22,19,9,10,20,11,12,13,37,38,39, %T A123495 40,41,42,43,44,45,46,47,48,49,50,58,59,62,63,64,56,60,51,23,24,52,25, %U A123495 26,27,57,61,53,28,29,54,30,31,32,55,33,34,35,36,107,108,109,110,111 %N A123495 Signature permutation of a nonrecursive Catalan automorphism: row 65518 of table A089840. %H A123495 A. Karttunen, <a href="/A089840/a089840p.txt">Prolog-program which illustrates the construction of this and other similar nonrecursive Catalan automorphisms.</a> %H A123495 <a href="/index/Per#IntegerPermutationCatAuto">Index entries for signature-permutations of Catalan automorphisms</a> %o A123495 (Scheme function, destructive implementation of this automorphism acting on S-expressions:) (define (*A123495! s) (cond ((null? s) s) ((and (pair? (car s)) (pair? (cdr s))) (*A069770! s) (*A074679! s)) (else (*A074679! s))) s) %Y A123495 Inverse: A123496. a(n) = A082351(A069770(n)). Row 65518 of A089840. Used to construct automorphism *A082357. Cf. A069770 and A074679. %K A123495 nonn %O A123495 0,3 %A A123495 _Antti Karttunen_, Oct 11 2006