%I
%S 1,2,7,18,31,98,127,450,511,1922,2047,7938,8191,32258,32767,130050,
%T 131071,522242,524287,2093058
%N Half the number of n X n toroidal binary arrays with each element having the sum of its vertical neighbors equal to the sum of its horizontal neighbors
%C Half the number of solutions in 0..1 of a 1d velocityone wave equation utt=uxx on a periodic grid
%C Diagonal of A184097
%F Empirical G.f.: x*(1+2*x2*x^2)*(1+2*x^2)/(1x)/(1+x)/(12*x)/(1+2*x)/(12*x^2). [Colin Barker, Feb 17 2012]
%e Some solutions for 5X5
%e ..1..0..0..1..1....1..0..0..0..1....1..0..0..0..0....1..1..1..0..0
%e ..0..0..1..1..1....1..1..0..0..0....0..1..0..0..0....0..1..1..1..0
%e ..0..1..1..1..0....0..1..1..0..0....0..0..1..0..0....0..0..1..1..1
%e ..1..1..1..0..0....0..0..1..1..0....0..0..0..1..0....1..0..0..1..1
%e ..1..1..0..0..1....0..0..0..1..1....0..0..0..0..1....1..1..0..0..1
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 09 2011
