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%I #9 Feb 06 2019 06:05:54
%S 0,9,52,364,2523,17424,120462,832701,5756112,39789720,275050323,
%T 1901312388,13143008754,90852339501,628025724756,4341289537476,
%U 30009590539371,207444243598344,1433978719090182,9912518810524413
%N Number of n X 2 0..2 arrays with every element plus 1 mod 3 equal to some element at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) (1,-1) or (1,0), with upper left element zero.
%H R. H. Hardin, <a href="/A278000/b278000.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 6*a(n-1) + 6*a(n-2) + 3*a(n-3) - 6*a(n-4).
%F Empirical g.f.: x^2*(9 - 2*x - 2*x^2) / (1 - 6*x - 6*x^2 - 3*x^3 + 6*x^4). - _Colin Barker_, Feb 06 2019
%e Some solutions for n=4:
%e ..0..0. .0..1. .0..1. .0..2. .0..1. .0..1. .0..1. .0..1. .0..2. .0..1
%e ..1..2. .2..0. .2..1. .1..1. .2..0. .2..1. .2..1. .2..0. .1..2. .1..2
%e ..2..1. .2..0. .2..0. .2..1. .1..1. .2..0. .1..0. .1..0. .1..2. .0..1
%e ..0..0. .1..0. .1..2. .0..0. .0..0. .1..0. .2..0. .1..2. .0..2. .0..2
%Y Column 2 of A278006.
%K nonn
%O 1,2
%A _R. H. Hardin_, Nov 08 2016
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