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%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