%I #5 Mar 31 2012 12:36:34
%S 1,5,1675,14520192,1683040515731
%N Number of 2nX2n 0..4 arrays with values 0..4 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors
%C Diagonal of A198253
%e Some solutions for n=3
%e ..0..0..1..1..2..2....0..0..1..1..2..2....0..0..1..1..2..2....0..0..1..1..0..0
%e ..0..0..1..1..2..2....0..0..1..1..2..2....0..0..1..1..2..2....0..0..1..1..0..0
%e ..1..1..2..2..3..3....1..1..2..2..3..3....3..3..2..2..4..4....1..1..0..0..2..2
%e ..1..1..2..2..3..3....1..1..2..2..3..3....3..3..2..2..4..4....1..1..0..0..2..2
%e ..4..4..0..0..4..4....2..2..0..0..4..4....4..4..0..0..3..3....2..2..3..3..1..1
%e ..4..4..0..0..4..4....2..2..0..0..4..4....4..4..0..0..3..3....2..2..3..3..1..1
%K nonn
%O 1,2
%A _R. H. Hardin_ Oct 22 2011