

A145208


Number of distinct shuffles of the identity permutation on n letters with the halfwaywrapped around permutation k+1,k+2,...,n1,n,1,2,...,k where k=floor(n/2).


0



1, 4, 13, 54, 197, 792, 2977, 11750, 44744, 175066, 671783, 2619148, 10104590
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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.


LINKS

Table of n, a(n) for n=1..13.


EXAMPLE

For n=2, the distinct shuffles of 12 with 21 are: 1221, 1212, 2112, 2121.


CROSSREFS

Sequence in context: A149466 A006604 A082570 * A149467 A149468 A149469
Adjacent sequences: A145205 A145206 A145207 * A145209 A145210 A145211


KEYWORD

nonn


AUTHOR

Camillia Smith Barnes, Oct 04 2008


STATUS

approved



