A190420 - OEIS

%I #7 Mar 31 2012 12:36:19

%S 44,363,6072,191360,10093200,935338785,154543989072,44556415740672,

%T 22668584136931568,20377347136466565883,32182451728510291871740,

%U 89502269428191719999392640,438593646987789744491801743584

%N Number of (n+2)X(n+2) symmetric binary matrices without the pattern 1 1 1 diagonally or antidiagonally

%H R. H. Hardin, <a href="/A190420/b190420.txt">Table of n, a(n) for n = 1..17</a>

%e Some solutions for n=2

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ May 10 2011