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%I #4 Oct 30 2013 17:05:51
%S 0,2,4,12,100,326,2114,9226,47220,233480,1135788,5678402,27785526,
%T 137642146,678271020,3346581344,16519160048,81474120774,402103867046,
%U 1983757394910,9788422760352,48296742499360,238296850975076
%N Number of nX3 0..2 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 3 and at least one element with value (x(i,j)-1) mod 3, and upper left element zero
%C Column 3 of A230819
%H R. H. Hardin, <a href="/A230814/b230814.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 6*a(n-1) -2*a(n-2) -19*a(n-3) -a(n-4) +169*a(n-5) -607*a(n-6) +913*a(n-7) -1279*a(n-8) +2352*a(n-9) -3003*a(n-10) +3418*a(n-11) -2775*a(n-12) +1279*a(n-13) -676*a(n-14) +156*a(n-15) -4*a(n-16) -62*a(n-17) +60*a(n-18) -12*a(n-19)
%e Some solutions for n=4
%e ..0..1..2....0..2..1....0..2..1....0..1..2....0..1..2....0..2..1....0..1..2
%e ..2..1..0....1..2..0....1..2..0....2..1..0....2..1..0....1..2..0....2..1..0
%e ..2..1..0....1..2..0....1..0..2....0..1..2....1..0..2....0..2..1....0..2..1
%e ..0..1..2....0..2..1....2..0..1....2..1..0....2..0..1....1..2..0....1..2..0
%K nonn
%O 1,2
%A _R. H. Hardin_, Oct 30 2013
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