|
%I #7 Dec 18 2015 18:17:42
%S 0,2,4,26,240,4063,110576,5046694,390350577,51445991632,
%T 11496127271424,4348804724288989,2784306483759192151,
%U 3019459887601073667024,5548682373331641079067391,17274304412990968236505863156
%N Number of n X n symmetric 0..1 arrays with each element equal to the product mod 2 of two of its horizontal and vertical neighbors
%H R. H. Hardin, <a href="/A193480/b193480.txt">Table of n, a(n) for n = 1..19</a>
%e Some solutions for 4X4
%e ..0..0..1..1....1..1..1..1....1..1..0..0....1..1..1..1....1..1..1..0
%e ..0..0..1..1....1..0..0..1....1..1..1..1....1..1..1..1....1..1..1..0
%e ..1..1..1..0....1..0..0..1....0..1..1..1....1..1..1..1....1..1..1..1
%e ..1..1..0..0....1..1..1..1....0..1..1..1....1..1..1..1....0..0..1..1
%K nonn
%O 1,2
%A _R. H. Hardin_ Jul 27 2011
| 