%I #7 Dec 11 2015 11:59:08
%S 256,2292,15564,95408,574364,3472540,21122008,129099360,792188532,
%T 4877980340,30132023264,186677124664,1159672904860,7222244911020,
%U 45083174298216,282019092305744,1767599836030724,11098250929281124
%N Number of (n+1) X 2 0..3 arrays with the number of clockwise edge increases in 2 X 2 subblocks nondecreasing, and counterclockwise edge increases nonincreasing, rightwards and downwards.
%C Column 1 of A206109.
%H R. H. Hardin, <a href="/A206102/b206102.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 16*a(n-1) - 87*a(n-2) + 174*a(n-3) - 15*a(n-4) - 420*a(n-5) + 607*a(n-6) - 346*a(n-7) + 72*a(n-8) for n>10.
%e Some solutions for n=4:
%e ..3..2....1..0....2..2....3..0....3..2....1..0....1..0....3..1....1..1....1..0
%e ..0..1....3..1....3..1....1..1....0..0....3..2....0..1....0..0....2..2....0..0
%e ..0..2....0..2....1..2....0..2....2..2....2..1....1..3....1..1....1..1....0..3
%e ..3..3....1..3....1..3....3..3....1..1....3..2....3..0....1..2....1..2....3..3
%e ..1..0....0..1....0..3....2..0....0..3....0..3....3..1....2..2....3..3....1..3
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 03 2012