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 A130375 #5 Mar 31 2012 13:21:14 %S A130375 0,1,2,3,5,4,6,7,8,11,12,13,10,9,14,15,16,17,18,19,20,21,22,29,28,30, %T A130375 31,32,33,34,35,25,26,36,27,24,23,38,37,39,40,41,42,43,44,45,46,47,48, %U A130375 49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,81,82,83,80,79,85,84 %N A130375 Signature permutation of a Catalan automorphism: apply *A074685 after the first nil on the top-level of list, if any present, otherwise leave the structure intact. %H A130375 A. Karttunen, <a href="/A130375/b130375.txt">Table of n, a(n) for n = 0..2055</a> %H A130375 <a href="/index/Per#IntegerPermutationCatAuto">Index entries for signature-permutations of Catalan automorphisms</a> %o A130375 (Destructive Scheme implementation of this automorphism, which acts on S-expressions, i.e. list-structures:) %o A130375 (define *A130375! (!APPLY-AFTER-FIRST-NIL *A074685!)) %o A130375 (define (!APPLY-AFTER-FIRST-NIL f!) (letrec ((g! (lambda (s) (cond ((pair? s) (if (pair? (car s)) (g! (cdr s)) (f! (cdr s))))) s))) g!)) %Y A130375 Inverse: A130376. a(n) = A074685(A130370(n)) = A074685(A130371(A074686(n))) = A130369(A130371(A130370(n))). %K A130375 nonn %O A130375 0,3 %A A130375 _Antti Karttunen_, Jun 05 2007