A146042 - OEIS

A146042

Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 2X4 tee 1,1 1,2 1,3 2,3 1,4 in any orientation.

%I #3 Mar 31 2012 12:35:09

%S 1,1,1,1,1,3,5,11,21,41,165,701,2953,12345,51325,344201,2572877,

%T 21631323,180106811,1718811817,19639803327,281005626019,4302161174593,

%U 75232261306781,1397819874484453,32083258430460691

%N Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 2X4 tee 1,1 1,2 1,3 2,3 1,4 in any orientation.

%e Maximal 8 X 8 example

%e .0.0.0.0.0.0.0.0

%e .0.0.1.1.1.1.0.0

%e .0.1.0.0.1.0.1.0

%e .0.1.0.0.0.1.1.0

%e .0.1.1.0.0.0.1.0

%e .0.1.0.1.0.0.1.0

%e .0.0.1.1.1.1.0.0

%e .0.0.0.0.0.0.0.0

%K nonn

%O 1,6

%A _R. H. Hardin_, Oct 26 2008