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 A069774 Permutation of natural numbers induced by the automorphism RoblDownCar_et_SwapInv! acting on the parenthesizations encoded by A014486. 7
 0, 1, 3, 2, 7, 8, 4, 6, 5, 17, 18, 20, 21, 22, 9, 10, 14, 16, 19, 11, 12, 15, 13, 45, 46, 48, 49, 50, 54, 55, 57, 58, 59, 61, 62, 63, 64, 23, 24, 25, 26, 27, 37, 38, 42, 44, 47, 51, 53, 56, 60, 28, 29, 30, 31, 32, 39, 40, 43, 52, 33, 34, 35, 41, 36, 129, 130, 132, 133, 134 (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 (RoblDownCar_et_SwapInv! s) (cond ((not (pair? s))) ((not (pair? (car s))) (swap! s)) (else (RoblDownCar_et_SwapInv! (car s)) (robr! 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 of A069773, the car/cdr-flipped conjugate of A057502, i.e. A069774(n) = A057163(A057502(A057163(n))). Cf. also A069776. Sequence in context: A074688 A130998 A130926 * A089861 A072092 A071659 Adjacent sequences:  A069771 A069772 A069773 * A069775 A069776 A069777 KEYWORD nonn AUTHOR Antti Karttunen, Apr 16 2002 STATUS approved

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Last modified May 26 22:22 EDT 2020. Contains 334634 sequences. (Running on oeis4.)