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Number of n X n binary arrays with all ones connected only in two by two blocks.
1

%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