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A007972 Number of permutations that are 2 "block reversals" away from 12...n. 0
2, 15, 52, 129, 266, 487 (list; graph; refs; listen; history; internal format)
OFFSET

3,1

CROSSREFS

Sequence in context: A154565 A066562 A073877 * A015520 A098520 A056078

Adjacent sequences:  A007969 A007970 A007971 * A007973 A007974 A007975

KEYWORD

nonn

AUTHOR

J. H. Conway (conway(AT)math.princeton.edu)

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Last modified February 16 17:48 EST 2012. Contains 205939 sequences.