login
Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation.
0

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

%S 1,1,1,1,13,19,471,1011,17363,51133,4227773,17426251,4189737457,

%T 23548416611,8347118368027,61971666176727,58964882823496375,

%U 583865226098623749,1588500435723596374221,21184137467738936180415

%N Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation.

%e Maximal 8 X 8 example

%e .1.1.0.0.0.0.1.1

%e .1.1.0.0.0.0.1.1

%e .1.0.0.0.0.0.0.1

%e .0.1.1.0.0.1.1.0

%e .0.1.1.0.0.1.1.0

%e .0.0.1.0.0.1.0.0

%e .1.1.0.0.0.0.1.1

%e .1.1.1.0.0.1.1.1

%K nonn

%O 1,5

%A _R. H. Hardin_, Oct 26 2008