A190533 - OEIS

%I #5 Mar 31 2012 12:36:19

%S 42,332,3660,59408,1405148,49455712,2586803564,202549927174,

%T 23737296725976,4174330956088592,1101527208080551428,

%U 436589349514722980996,259916332325245438667936

%N Number of (n+2)X(n+2) symmetric binary matrices without the pattern 0 1 1 vertically or horizontally

%H R. H. Hardin, <a href="/A190533/b190533.txt">Table of n, a(n) for n = 1..19</a>

%e Some solutions for 4X4

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ May 12 2011