A190416 - OEIS

%I #8 Mar 31 2012 12:36:19

%S 48,432,7776,279936,18475776,2235568896,491825157120,196730062848000,

%T 145580246507520000,199299357468794880000,501437183391487918080000,

%U 2318645536002240133201920000,19708487056019041132216320000000

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

%H R. H. Hardin, <a href="/A190416/b190416.txt">Table of n, a(n) for n = 1..58</a>

%e Some solutions for n=2

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ May 10 2011