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 A071657 Permutation of natural numbers induced by the automorphism car_robr_cdr! acting on the parenthesizations encoded by A014486. 8
 0, 1, 3, 2, 7, 8, 5, 6, 4, 17, 18, 20, 21, 22, 12, 13, 15, 16, 19, 10, 9, 14, 11, 45, 46, 48, 49, 50, 54, 55, 57, 58, 59, 61, 62, 63, 64, 31, 32, 34, 35, 36, 40, 41, 43, 44, 47, 52, 53, 56, 60, 26, 27, 24, 28, 25, 38, 37, 42, 51, 29, 33, 30, 39, 23, 129, 130, 132, 133, 134 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS A. Karttunen, Gatomorphisms (Includes the complete Scheme source for computing this sequence) PROG (Scheme function implementing this automorphism on list-structures:) (define (car_robr_cdr! s) (cond ((not (pair? s))) ((not (pair? (car s))) (swap! s)) (else (car_robr_cdr! (car s)) (robr! s) (car_robr_cdr! (cdr s)))) s) (define (robr! s) (let ((ex-cdr (cdr s))) (set-cdr! s (caar s)) (set-car! (car s) ex-cdr) (swap! (car s)) (swap! s) s)) (define (swap! s) (let ((ex-car (car s))) (set-car! s (cdr s)) (set-cdr! s ex-car) s)) CROSSREFS Inverse permutation: A071658 and also its car/cdr-flipped conjugate, i.e. A071657(n) = A057163(A071658(A057163(n))). Cf. also A071655, A071656, A071659, A071660. Sequence in context: A130953 A130396 A131010 * A057161 A130363 A089862 Adjacent sequences:  A071654 A071655 A071656 * A071658 A071659 A071660 KEYWORD nonn AUTHOR Antti Karttunen, May 30 2002 STATUS approved

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Last modified October 23 19:37 EDT 2019. Contains 328373 sequences. (Running on oeis4.)