%I #8 Mar 09 2015 04:29:13
%S 1,2,12,52,1992,43472,8084672,785972800,632010796352,260819509251776,
%T 879345967412550400,1508148706710022883840,20993821611583601278837888,
%U 147923394778079541856196475392,8426633557858801012990635249817088
%N Half the number of symmetric n X n binary matrices with the center of gravity of the 1s at the center.
%H R. H. Hardin, Jun 01 2008, <a href="/A139046/b139046.txt">Table of n, a(n) for n = 1..19</a>
%Y Cf. A133413.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jun 01 2008