cp's OEIS Frontend

A089857 Permutation of natural numbers induced by Catalan Automorphism *A089857 acting on the binary trees/parenthesizations encoded by A014486/A063171.

%I A089857 #21 May 01 2018 02:42:51
%S A089857 0,1,2,3,4,5,8,6,7,9,10,11,12,13,21,22,19,14,15,20,16,17,18,23,24,25,
%T A089857 26,27,28,29,30,31,32,33,34,35,36,58,59,62,63,64,56,60,51,37,38,52,39,
%U A089857 40,41,57,61,53,42,43,54,44,45,46,55,47,48,49,50,65,66,67,68,69,70,71,72
%N A089857 Permutation of natural numbers induced by Catalan Automorphism *A089857 acting on the binary trees/parenthesizations encoded by A014486/A063171.
%C A089857 .A...B...........C...A
%C A089857 ..\./.............\./
%C A089857 ...x...C....-->....x...B...............()..A.........()..A..
%C A089857 ....\./.............\./.................\./....-->....\./...
%C A089857 .....x...............x...................x.............x....
%C A089857 ((a . b) . c) -> ((c . a) . b) _____ (() . a) ---> (() . a)
%C A089857 In terms of S-expressions, this automorphism rotates caar, cdar and cdr of an S-exp, i.e., if car-side is not ().
%C A089857 See the Karttunen OEIS-Wiki link for a detailed explanation how to obtain a given integer sequence from this definition.
%H A089857 A. Karttunen, <a href="http://oeis.org/wiki/Catalan_Automorphisms">Catalan Automorphisms</a>
%H A089857 A. Karttunen, <a href="/A089408/a089408.c.txt">C-program for computing this sequence</a>
%H A089857 <a href="/index/Per#IntegerPermutationCatAuto">Index entries for signature-permutations induced by Catalan automorphisms</a>
%o A089857 (Scheme functions implementing this automorphism on list-structures/S-expressions, both constructive (*A089857) and destructive (*A089857!) versions:)
%o A089857 (define (*A089857 s) (if (and (pair? s) (pair? (car s))) (cons (cons (cdr s) (caar s)) (cdar s)) s))
%o A089857 (define (*A089857! s) (cond ((not (pair? s)) s) ((not (pair? (car s))) s) (else (swap! s) (robl! s) s)))
%o A089857 (define (swap! s) (let ((ex-car (car s))) (set-car! s (cdr s)) (set-cdr! s ex-car) s))
%o A089857 (define (robl! s) (let ((ex-car (car s))) (set-car! s (cddr s)) (set-cdr! (cdr s) ex-car) (swap! (cdr s)) (swap! s) s))
%Y A089857 Row 11 of A089840. Inverse of A089855. a(n) = A074679(A069770(n)) = A069770(A089862(n)) = A057163(A089851(A057163(n))).
%Y A089857 Number of cycles: A089847. Number of fixed-points: A089848 (in each range limited by A014137 and A014138).
%K A089857 nonn
%O A089857 0,3
%A A089857 _Antti Karttunen_, Nov 29 2003
%E A089857 Further comments and constructive implementation of Scheme-function (*A089857) added by _Antti Karttunen_, Jun 04 2011