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A145208
Number of distinct shuffles of the identity permutation on n letters with the halfway-wrapped around permutation k+1,k+2,...,n-1,n,1,2,...,k where k=floor(n/2).
0
1, 4, 13, 54, 197, 792, 2977, 11750, 44744, 175066, 671783, 2619148, 10104590
OFFSET
1,2
COMMENTS
A complicated formula has been found but needs to be simplified before entering here; also, a Maple program is on the way.
REFERENCES
C. Smith, dissertation, Harvard University, forthcoming.
EXAMPLE
For n=2, the distinct shuffles of 12 with 21 are: 1221, 1212, 2112, 2121.
CROSSREFS
Sequence in context: A369226 A006604 A082570 * A149467 A149468 A149469
KEYWORD
nonn
AUTHOR
STATUS
approved