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%I #9 Sep 14 2018 15:59:06
%S 8,30,126,518,2138,8818,36374,150038,618890,2552850,10530214,43435926,
%T 179168218,739048370,3048489846,12574671318,51869078378,213954005138,
%U 882535756294,3640358873558,15016063240250,61939540321970
%N Number of n X 2 0..2 arrays avoiding 11 horizontally, 22 vertically and 00 diagonally or antidiagonally.
%H R. H. Hardin, <a href="/A229374/b229374.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) + a(n-2) - 2*a(n-3).
%F Empirical g.f.: 2*x*(4 - x - x^2) / (1 - 4*x - x^2 + 2*x^3). - _Colin Barker_, Sep 14 2018
%e Some solutions for n=4:
%e 1 0 1 0 1 2 0 2 2 1 1 0 0 1 2 0 0 1 0 1
%e 1 2 2 2 2 0 2 1 0 1 2 1 2 1 1 2 1 2 2 1
%e 0 1 0 1 1 2 0 1 2 1 0 0 0 0 2 1 0 1 0 1
%e 0 1 1 2 0 1 0 1 1 0 1 2 2 2 0 0 1 2 0 1
%Y Column 2 of A229380.
%K nonn
%O 1,1
%A _R. H. Hardin_, Sep 21 2013
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