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Number of (n+2)X(n+2) symmetric binary matrices without the pattern 1 1 1 vertically, antidiagonally or horizontally
1

%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