A072095 - OEIS

A072095

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

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, 42, 43, 48, 47, 49, 40, 39, 50, 41, 37, 38, 54, 53, 55, 52, 51, 57, 56, 58, 23, 24, 59, 25, 26, 27, 61, 60, 62, 28, 29, 63, 30, 31, 32, 64, 33, 34, 35, 36, 129, 128, 130, 127, 126

(list; graph; refs; listen; history; text; internal format)

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 (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)

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

Sequence in context: A071656 A130963 A130930 * A131009 A129609 A130924

Adjacent sequences: A072092 A072093 A072094 * A072096 A072097 A072098

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jun 25 2002

STATUS

approved