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A205817 Number of (n+1) X 3 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock unequal to the number of counterclockwise edge increases.

%I A205817 #12 Jun 12 2018 11:12:29
%S A205817 66,216,714,2430,8274,28242,96402,329130,1123698,3836538,13098738,
%T A205817 44721882,152690034,521316378,1779885426,6076908954,20747864946,
%U A205817 70837641882,241854837618,825744066714,2819266591602,9625578232986
%N A205817 Number of (n+1) X 3 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock unequal to the number of counterclockwise edge increases.
%C A205817 Column 2 of A205823.
%H A205817 R. H. Hardin, <a href="/A205817/b205817.txt">Table of n, a(n) for n = 1..210</a>
%F A205817 Empirical: a(n) = 4*a(n-1) - a(n-2) - 4*a(n-3) + 2*a(n-4).
%F A205817 Empirical g.f.: 6*x*(11 - 8*x - 14*x^2 + 9*x^3) / ((1 - x)*(1 + x)*(1 - 4*x + 2*x^2)). - _Colin Barker_, Jun 12 2018
%e A205817 Some solutions for n=4:
%e A205817 ..2..0..0....1..2..2....2..0..0....1..1..1....2..1..2....1..0..1....0..0..2
%e A205817 ..2..1..2....0..0..1....2..1..2....2..0..2....0..1..0....2..0..2....2..1..1
%e A205817 ..2..0..2....1..2..1....2..0..2....2..1..1....2..1..2....1..0..1....2..0..2
%e A205817 ..2..1..1....0..0..0....1..0..1....2..0..2....0..1..0....1..2..1....1..0..1
%e A205817 ..2..0..2....2..1..2....1..2..1....1..1..2....0..2..2....0..2..0....1..2..1
%Y A205817 Cf. A205823.
%K A205817 nonn
%O A205817 1,1
%A A205817 _R. H. Hardin_, Feb 01 2012