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 A072095 Permutation of natural numbers induced by the automorphism cdr_robl_cdr! acting on the parenthesizations encoded by A014486. 6

%I

%S 0,1,3,2,7,6,8,4,5,17,16,18,15,14,20,19,21,9,10,22,11,12,13,45,44,46,

%T 42,43,48,47,49,40,39,50,41,37,38,54,53,55,52,51,57,56,58,23,24,59,25,

%U 26,27,61,60,62,28,29,63,30,31,32,64,33,34,35,36,129,128,130,127,126

%N Permutation of natural numbers induced by the automorphism cdr_robl_cdr! acting on the parenthesizations encoded by A014486.

%H A. Karttunen, <a href="http://www.iki.fi/~kartturi/matikka/Nekomorphisms/gatomorf.htm">Gatomorphisms</a> (Includes the complete Scheme program for computing this sequence)

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%o (Scheme function implementing this automorphism on list-structures:)

%o (define (cdr_robl_cdr! s) (cond ((not (pair? s))) ((not (pair? (cdr s))) (swap! s)) (else (cdr_robl_cdr! (cdr s)) (robl! s) (cdr_robl_cdr! (cdr s)))) s)

%o (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))

%o (define (swap! s) (let ((ex-car (car s))) (set-car! s (cdr s)) (set-cdr! s ex-car) s))

%Y Inverse permutation: A072094. The car/cdr-flipped conjugate of A072092, i.e. A072095(n) = A057163(A072092(A057163(n))). Cf. also A071655-A071660, A072090-A072091.

%K nonn

%O 0,3

%A _Antti Karttunen_, Jun 25 2002

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Last modified February 19 07:51 EST 2019. Contains 320309 sequences. (Running on oeis4.)