%I #5 Mar 31 2012 12:37:29
%S 175,2710,40600,614935,9278940,140274002,2118517533,32012611741,
%T 483591817235,7306527081148,110382673709151,1667687996584917,
%U 25195038977801100,380647562549584423,5750778390043860484
%N 1/4 the number of (n+1)X3 0..3 arrays with every 2X2 subblock having distinct clockwise edge differences
%C Column 2 of A209716
%H R. H. Hardin, <a href="/A209710/b209710.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 9*a(n-1) +155*a(n-2) -718*a(n-3) -5017*a(n-4) +21111*a(n-5) +51148*a(n-6) -251141*a(n-7) -85963*a(n-8) +1092718*a(n-9) -438881*a(n-10) -1923975*a(n-11) +1461077*a(n-12) +1300250*a(n-13) -1385402*a(n-14) -184926*a(n-15) +434126*a(n-16) -73408*a(n-17) -12888*a(n-18) +1440*a(n-19)
%e Some solutions for n=4
%e ..0..1..0....3..3..1....3..1..1....0..3..0....1..0..0....1..1..3....2..0..0
%e ..0..3..0....0..1..0....3..0..3....2..0..1....3..1..3....0..3..0....2..3..1
%e ..3..1..1....3..1..3....1..1..0....1..2..3....0..1..0....0..1..0....3..1..0
%e ..1..0..3....1..0..2....3..0..3....2..0..0....1..3..2....0..3..1....0..1..3
%e ..3..0..1....3..0..3....3..1..0....3..2..3....3..2..0....3..1..0....2..3..2
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 11 2012