%I #5 Mar 31 2012 12:36:34
%S 1,4,100,8784,2823604,3337609528
%N Number of 2nX2n 0..2 arrays with values 0..2 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors
%C Diagonal of A198285
%e Some solutions for n=3
%e ..0..0..1..1..2..2....0..0..1..1..1..1....0..0..1..1..0..0....0..0..1..1..0..0
%e ..0..0..1..1..2..2....0..0..1..0..0..1....0..0..1..1..0..0....0..0..1..1..0..0
%e ..1..1..2..2..0..0....2..2..1..0..0..1....1..1..0..0..2..2....1..1..0..0..1..1
%e ..1..1..2..2..0..0....2..2..1..2..2..1....1..1..0..0..2..2....1..1..0..0..1..1
%e ..2..2..1..1..2..2....0..0..1..2..2..1....2..2..1..1..0..0....0..0..1..1..0..0
%e ..2..2..1..1..2..2....0..0..1..1..1..1....2..2..1..1..0..0....0..0..1..1..0..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Oct 23 2011
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