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A231213 Number of (n+1) X (2+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and vertical neighbors, with values 0..2 introduced in row major order.

%I A231213 #9 Sep 27 2018 19:49:28
%S A231213 4,9,22,59,156,413,1098,2919,7760,20633,54862,145875,387876,1031349,
%T A231213 2742322,7291743,19388504,51553393,137078774,364487947,969161452,
%U A231213 2576968397,6852074138,18219439575,48444890080,128813368009,342510505246
%N A231213 Number of (n+1) X (2+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and vertical neighbors, with values 0..2 introduced in row major order.
%H A231213 R. H. Hardin, <a href="/A231213/b231213.txt">Table of n, a(n) for n = 1..210</a>
%F A231213 Empirical: a(n) = 3*a(n-1) - a(n-2) + a(n-3) - 2*a(n-4).
%F A231213 Empirical g.f.: x*(4 - 3*x - x^2 - 2*x^3) / ((1 - x)*(1 - 2*x - x^2 - 2*x^3)). - _Colin Barker_, Sep 27 2018
%e A231213 Some solutions for n=4:
%e A231213 ..0..1..1....0..0..0....0..0..1....0..0..1....0..1..1....0..0..0....0..0..1
%e A231213 ..0..1..1....0..0..0....0..0..1....0..0..1....0..1..1....1..1..0....0..0..1
%e A231213 ..0..2..2....0..0..0....0..0..1....0..1..1....0..1..1....1..1..0....2..2..1
%e A231213 ..0..2..2....0..0..0....0..1..1....0..1..1....0..0..1....1..1..0....2..2..1
%e A231213 ..0..2..2....0..0..0....0..1..1....0..0..0....0..0..1....1..1..0....2..2..1
%Y A231213 Column 2 of A231219.
%K A231213 nonn
%O A231213 1,1
%A A231213 _R. H. Hardin_, Nov 05 2013