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%I #6 Aug 12 2016 06:53:59
%S 1,2,6,20,83,410,2109,11097,59698,325240,1786820,9888567,55061514,
%T 308166631,1732444205,9777801332,55377818912,314616215640,
%U 1792424007975,10237590562396,58607205582421,336211631539125,1932440491804486
%N Number of 3Xn arrays containing n copies of 0..3-1 with no element 1 greater than its north or northeast neighbor modulo 3 and the upper left element equal to 0.
%C Row 3 of A266599.
%H R. H. Hardin, <a href="/A266600/b266600.txt">Table of n, a(n) for n = 1..102</a>
%e Some solutions for n=4
%e ..0..2..2..2....0..0..2..2....0..2..1..0....0..1..0..2....0..1..2..0
%e ..2..1..1..1....0..2..1..1....2..1..0..2....0..0..2..1....0..1..2..2
%e ..1..0..0..0....2..1..0..1....1..0..2..1....2..2..1..1....0..1..1..2
%Y Cf. A266599.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 01 2016
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