A190626 - OEIS

%I #5 Dec 18 2015 18:17:38

%S 1,0,2,6,42,324,4092,76160,2171670,91674436,5732036632,535081395254,

%T 74600276538996,15457006345833026,4764968523827845468,

%U 2185341275223905432960,1490580025901441886543202

%N Half the number of n X n symmetric binary matrices with no element equal to a strict majority of its diagonal and antidiagonal neighbors

%e Some solutions for n=4 with a(1,1)=0

%e ..0..1..1..1....0..0..0..0....0..0..1..0....0..1..0..1....0..1..0..1

%e ..1..1..0..0....0..1..1..0....0..1..1..0....1..1..0..0....1..1..0..1

%e ..1..0..0..1....0..1..1..0....1..1..0..0....0..0..1..1....0..0..0..1

%e ..1..0..1..1....0..0..0..0....0..0..0..1....1..0..1..0....1..1..1..1

%K nonn

%O 1,3

%A _R. H. Hardin_ May 14 2011