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%I #5 Mar 31 2012 12:36:34
%S 2,32,674,14396,309770,6671450,143724590,3096625676,66720604082,
%T 1437592096184,30975107870150,667406503209962,14380307969705594,
%U 309846066281809304,6676114885818492290,143847269049688259540
%N Number of 2nX6 0..3 arrays with values 0..3 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors
%C Column 3 of A198604
%H R. H. Hardin, <a href="/A198599/b198599.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 27*a(n-1) -107*a(n-2) -164*a(n-3) -1701*a(n-4) +7073*a(n-5) +13206*a(n-6) +22329*a(n-7) -67473*a(n-8) -190188*a(n-9) -20655*a(n-10) +60507*a(n-11) +177147*a(n-12)
%e Some solutions for n=4
%e ..0..0..1..1..0..0....0..0..1..1..2..2....0..0..1..1..0..0....0..0..1..1..2..2
%e ..0..0..1..1..0..0....0..0..1..1..2..2....0..0..1..1..0..0....0..0..1..1..2..2
%e ..2..2..0..0..3..3....1..1..2..2..0..0....2..2..3..3..1..1....1..1..0..0..3..3
%e ..2..2..0..0..3..3....1..1..2..2..0..0....2..2..3..3..1..1....1..1..0..0..3..3
%e ..0..0..2..2..1..1....2..2..0..0..3..3....0..0..1..1..0..0....3..3..1..1..0..0
%e ..0..0..2..2..1..1....2..2..0..0..3..3....0..0..1..1..0..0....3..3..1..1..0..0
%e ..3..3..1..1..3..3....1..1..3..3..1..1....1..1..0..0..2..2....1..1..2..2..3..3
%e ..3..3..1..1..3..3....1..1..3..3..1..1....1..1..0..0..2..2....1..1..2..2..3..3
%K nonn
%O 1,1
%A _R. H. Hardin_ Oct 27 2011
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