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A048200
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Minimal length pair-exchange / set-rotate sequence to reverse n distinct ordered elements.
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3
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0, 1, 2, 4, 10, 15, 23, 32, 42, 55, 67, 84
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,3
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COMMENTS
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"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.
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LINKS
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FORMULA
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EXAMPLE
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a(4) = 4 since "xrrx" is the shortest sequence reversing "ABCD". Explicitly, (begin) ABCD, (x)-> BACD, (r)-> ACDB, (r) -> CDBA, (x)-> DCBA.
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CROSSREFS
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KEYWORD
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nonn,nice,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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