%I
%S 1,2,3,4,10,12,52,58,394,418
%N Number of signed permutations invariant under the reverse complement and avoiding (2, 1), (1, 2), and (1, 2).
%F a(n) = (\lfloor n/2\rfloor)! 2^{\lfloor n/2\rfloor} + \sum_{k=0}^{\lfloor n/2\lceil} k!
%e For n = 3, the permutations are (1, 2, 3), (3, 2, 1), (1, 2, 3), and (3, 2, 1).
%K nonn
%O 0,2
%A _Andy Hardt_, Aug 04 2011
