%I #7 Mar 31 2012 12:36:19
%S 37,290,4174,103218,4268160,302857233,36530501839,7448773789365,
%T 2604518117252310,1552614799946248963,1570623177380821866672,
%U 2710542814101229129928033,7970415278138699394079102815
%N Number of (n+2)X(n+2) symmetric binary matrices without the pattern 1 1 1 vertically, antidiagonally or horizontally
%H R. H. Hardin, <a href="/A190418/b190418.txt">Table of n, a(n) for n = 1..23</a>
%e Some solutions for n=2
%e ..0..1..1..0....1..1..0..1....0..0..0..1....0..1..0..1....0..0..0..1
%e ..1..0..0..0....1..0..0..0....0..1..0..0....1..1..0..0....0..1..0..0
%e ..1..0..0..1....0..0..0..1....0..0..0..0....0..0..0..0....0..0..1..1
%e ..0..0..1..0....1..0..1..0....1..0..0..0....1..0..0..0....1..0..1..1
%K nonn
%O 1,1
%A _R. H. Hardin_ May 10 2011