

A048200


Minimal length pairexchange / setrotate sequence to reverse n distinct ordered elements.


2




OFFSET

1,3


COMMENTS

"Rotate" is always a leftrotate (moves leftmost element to the right end) and "Exchange" is always a pairexchange of the two leftmost elements.


LINKS

Table of n, a(n) for n=1..10.


EXAMPLE

a(4) = 4 since "xrrx" is the shortest sequence reversing "ABCD". Explicitly, (begin) ABCD, (x)> BACD, (r)> ACDB, (r) > CDBA, (x)> DCBA.


CROSSREFS

Sequence in context: A080149 A217134 A128513 * A058201 A000947 A125245
Adjacent sequences: A048197 A048198 A048199 * A048201 A048202 A048203


KEYWORD

nonn,nice,more


AUTHOR

Tony Bartoletti


EXTENSIONS

55 added by Tony Bartoletti, Feb 22 2011


STATUS

approved



