A072091 Permutation of natural numbers induced by the automorphism car_robl_cdr! acting on the parenthesizations encoded by A014486.

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

Offset

0,3

Links

Table of n, a(n) for n=0..69.

A. Karttunen, Gatomorphisms (Includes the complete Scheme program for computing this sequence)

Index entries for sequences that are permutations of the natural numbers

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