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A048200 Minimal length pair-exchange / set-rotate sequence to reverse n distinct ordered elements. 2
0, 1, 2, 4, 10, 15, 23, 32, 42, 55 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

"Rotate" is always a left-rotate (moves leftmost element to the right end) and "Exchange" is always a pair-exchange 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 A218211

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

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Last modified May 29 01:07 EDT 2017. Contains 287241 sequences.