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A232289 Number of nX2 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or antidiagonally.

%I A232289 #8 Jul 23 2025 07:15:35
%S A232289 3,15,73,355,1727,8401,40867,198799,967065,4704323,22884351,111321761,
%T A232289 541528771,2634286479,12814582761,62337005731,303240640447,
%U A232289 1475125167473,7175800237411,34906942259983,169806095157049,826027949905539
%N A232289 Number of nX2 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or antidiagonally.
%C A232289 Column 2 of A232295
%H A232289 R. H. Hardin, <a href="/A232289/b232289.txt">Table of n, a(n) for n = 1..210</a>
%F A232289 Empirical: a(n) = 4*a(n-1) +4*a(n-2) +a(n-3).
%F A232289 Empirical: G.f.: -x*(3+3*x+x^2) / ( -1+4*x+4*x^2+x^3 ). - _R. J. Mathar_, Nov 27 2013
%e A232289 Some solutions for n=7
%e A232289 ..2..2....2..1....2..2....2..2....2..2....2..2....1..2....1..2....1..2....1..2
%e A232289 ..2..0....0..2....2..0....2..1....0..1....2..1....0..1....1..0....2..1....2..0
%e A232289 ..1..2....2..0....1..2....1..2....2..1....2..1....2..1....2..2....1..2....1..2
%e A232289 ..2..2....1..2....2..0....2..2....0..2....2..2....0..2....2..1....2..1....1..2
%e A232289 ..1..2....2..1....1..2....2..2....0..1....2..1....1..0....0..0....1..2....1..1
%e A232289 ..2..0....0..1....1..2....1..2....2..1....2..1....0..1....1..2....2..2....2..1
%e A232289 ..1..2....2..2....2..1....1..2....2..2....0..2....2..2....2..2....2..1....2..2
%K A232289 nonn
%O A232289 1,1
%A A232289 _R. H. Hardin_, Nov 22 2013