%I #9 Jul 14 2018 05:56:11
%S 33,313,2908,27129,252951,2358878,21997263,205132657,1912938102,
%T 17838863745,166354085323,1551314182238,14466586111383,
%U 134906337113945,1258052152683182,11731807807607937,109403504572460163
%N 1/4 the number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having one or three distinct clockwise edge differences.
%C Column 1 of A210077.
%H R. H. Hardin, <a href="/A210070/b210070.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 9*a(n-1) + 9*a(n-2) - 50*a(n-3) - 54*a(n-4) + 12*a(n-5) + 16*a(n-6).
%F Empirical g.f.: x*(33 + 16*x - 206*x^2 - 210*x^3 + 50*x^4 + 64*x^5) / (1 - 9*x - 9*x^2 + 50*x^3 + 54*x^4 - 12*x^5 - 16*x^6). - _Colin Barker_, Jul 14 2018
%e Some solutions for n=4:
%e ..3..3....3..0....1..1....3..1....3..3....2..0....1..2....2..1....1..0....0..0
%e ..3..2....0..0....1..3....3..3....0..3....2..2....0..2....0..0....0..0....1..0
%e ..1..2....1..0....3..3....1..1....0..0....1..1....0..0....3..0....0..3....2..0
%e ..1..1....2..0....1..3....3..1....3..3....0..1....0..0....0..0....2..1....2..1
%e ..3..1....1..0....1..3....1..1....3..1....1..1....3..0....1..1....0..1....1..1
%Y Cf. A210077.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 17 2012