%I #6 Mar 31 2012 12:36:34

%S 12,206,3838,74582,1481214,29737425,600187403,12144602583,

%T 246046084954,4987787543526,101140166737445,2051157938501522,

%U 41600949234763960,843764349062814286,17113771581568185569,347115075675201580800

%N Number of 2nX4 0..2 arrays with values 0..2 introduced in row major order and each element equal to exactly one horizontal or vertical neighbor

%C Column 2 of A198532

%H R. H. Hardin, <a href="/A198529/b198529.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 42*a(n-1) -599*a(n-2) +3637*a(n-3) -8567*a(n-4) -1138*a(n-5) +28475*a(n-6) -23674*a(n-7) -2916*a(n-8) +112776*a(n-9) -163480*a(n-10) -147783*a(n-11) -101412*a(n-12) -148912*a(n-13) +747248*a(n-14) +967680*a(n-15) -1452032*a(n-16) -4042752*a(n-17) -7405568*a(n-18) -7340032*a(n-19) -4194304*a(n-20)

%e Some solutions for n=3

%e ..0..1..2..0....0..1..1..0....0..0..1..2....0..1..0..0....0..0..1..1

%e ..0..1..2..0....0..2..2..0....2..2..1..2....0..1..2..2....2..2..0..0

%e ..2..0..0..2....1..1..0..2....0..0..2..1....1..0..1..1....1..1..2..2

%e ..2..1..1..2....2..2..0..2....1..1..2..1....1..0..2..2....2..2..1..1

%e ..0..2..0..1....0..0..2..0....2..2..0..0....0..1..1..0....1..1..0..0

%e ..0..2..0..1....1..1..2..0....0..0..1..1....0..2..2..0....0..0..2..2

%K nonn

%O 1,1

%A _R. H. Hardin_ Oct 26 2011