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 A130339 #5 Mar 31 2012 13:21:14 %S A130339 0,1,2,3,4,6,5,7,8,9,10,11,16,19,14,15,12,17,18,13,20,21,22,23,25,24, %T A130339 26,27,28,29,30,44,47,33,53,56,60,37,38,39,43,52,42,40,31,45,46,32,48, %U A130339 49,50,51,41,34,54,55,35,57,58,59,36,61,62,63,64,65,66,67,72,75,70,71 %N A130339 Signature permutation of a Catalan automorphism: swap the two rightmost subtrees of general trees, if the root degree (A057515(n)) is even. %C A130339 This self-inverse automorphism is obtained as either SPINE(*A129608) or ENIPS(*A129608). See the definitions given in A122203 and A122204. %H A130339 A. Karttunen, <a href="/A130339/b130339.txt">Table of n, a(n) for n = 0..2055</a> %H A130339 <a href="/index/Per#IntegerPermutationCatAuto">Index entries for signature-permutations of Catalan automorphisms</a> %o A130339 (Destructive Scheme implementation of this automorphism, which acts on S-expressions, i.e. list-structures:) %o A130339 (define (*A130339! s) (if (even? (length s)) (*A129608! s)) s) %Y A130339 Cf. a(n) = A057508(A130340(A057508(n))) = A057164(A130340(A057164(n))). Row 3608 of A122285 and A122286. a(n) = A129608(n), if A057515(n) mod 2 = 0, otherwise a(n)=n. %K A130339 nonn %O A130339 0,3 %A A130339 _Antti Karttunen_, Jun 05 2007