A145208 - OEIS

%I #5 Oct 13 2013 20:21:37

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

%N 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).

%C A complicated formula has been found but needs to be simplified before entering here; also, a Maple program is on the way.

%D C. Smith, dissertation, Harvard University, forthcoming.

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

%K nonn

%O 1,2

%A _Camillia Smith Barnes_, Oct 04 2008