%I #3 Mar 31 2012 12:35:08
%S 1,2,5,12,72,513,4531,68662,1429824,40840428,1747979822,106711196102,
%T 9237029528023,1158315077977449,208422835867809541,
%U 53674442198900292691,19878424340459715152560,10569643478952360023168707
%N Number of n X n binary arrays with all ones connected only in two by two blocks.
%e Maximal 7 X 7 example
%e .0.0.0.1.1.0.0
%e .1.1.0.1.1.0.0
%e .1.1.0.0.0.1.1
%e .0.0.1.1.0.1.1
%e .0.0.1.1.0.0.0
%e .1.1.0.0.0.1.1
%e .1.1.0.0.0.1.1
%K nonn
%O 1,2
%A _R. H. Hardin_, Oct 22 2008