A146046 - OEIS

A146046

Number of n X n binary arrays with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation.

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

%S 1,1,17,57,781,24351,931801,62200649,8963823755,2146203654665,

%T 870522837091137,672438522925983773

%N Number of n X n binary arrays 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 .1.1.0.1.1.1.0.0

%e .1.1.0.1.1.0.1.1

%e .1.0.1.0.0.0.1.1

%e .0.1.1.0.1.1.0.1

%e .0.1.1.0.1.1.0.0

%e .1.0.0.1.0.1.0.1

%e .1.1.0.1.1.0.1.1

%K nonn

%O 1,3

%A _R. H. Hardin_, Oct 26 2008