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 A072091 Permutation of natural numbers induced by the automorphism car_robl_cdr! acting on the parenthesizations encoded by A014486. 7
 0, 1, 3, 2, 6, 7, 8, 4, 5, 15, 14, 16, 17, 18, 19, 20, 22, 9, 10, 21, 11, 12, 13, 39, 40, 41, 37, 38, 43, 42, 44, 45, 46, 47, 48, 49, 50, 52, 51, 53, 54, 55, 60, 61, 62, 23, 24, 63, 25, 26, 27, 56, 57, 64, 28, 29, 58, 30, 31, 32, 59, 33, 34, 35, 36, 113, 112, 114, 115, 116 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS A. Karttunen, Gatomorphisms (Includes the complete Scheme program for computing this sequence) PROG (Scheme function implementing this automorphism on list-structures:) (define (car_robl_cdr! s) (cond ((not (pair? s))) ((not (pair? (cdr s))) (swap! s)) (else (car_robl_cdr! (car s)) (robl! s) (car_robl_cdr! (cdr s)))) s) (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)) (define (swap! s) (let ((ex-car (car s))) (set-car! s (cdr s)) (set-cdr! s ex-car) s)) CROSSREFS Inverse permutation: A072090 and also its car/cdr-flipped conjugate, i.e. A072091(n) = A057163(A072090(A057163(n))). Cf. also A071655-A071660, A072092-A072095. Sequence in context: A122323 A123495 A130369 * A074687 A130366 A130934 Adjacent sequences:  A072088 A072089 A072090 * A072092 A072093 A072094 KEYWORD nonn AUTHOR Antti Karttunen, Jun 25 2002 STATUS approved

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Last modified October 14 14:35 EDT 2019. Contains 328019 sequences. (Running on oeis4.)