%I #8 Mar 30 2012 17:37:01
%S 2,4,24,192,1920,23040,322560,5160960,92897280,1857945600,40874803200,
%T 980995276800,25505877196800,714164561510400,21424936845312000,
%U 685597979049984000,23310331287699456000
%N Number of reversible strings with n labeled beads of 2 colors.
%H C. G. Bower, <a href="/transforms2.html">Transforms (2)</a>
%F 2^(n-1)*n! (n>1). E.g.f.: (1-2*x^2)/(1-2*x). Also "BIJ" (reversible, indistinct, labeled) transform of 2, 0, 0, 0...
%K nonn
%O 1,1
%A _Christian G. Bower_
%E Essentially same as A002866.