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%I #6 Aug 12 2016 06:53:59
%S 2,5,15,59,257,1205,5879,29693,153097,806375,4307317,23313947,
%T 127420533,702562447,3900415155,21786817517,122309555899,689707853981,
%U 3904123962093,22174631940293,126322762595339,721552901977497
%N Number of 3Xn arrays containing n copies of 0..3-1 with no element 1 greater than its northwest or northeast neighbor modulo 3 and the upper left element equal to 0.
%C Row 3 of A266681.
%H R. H. Hardin, <a href="/A266682/b266682.txt">Table of n, a(n) for n = 1..72</a>
%e Some solutions for n=4
%e ..0..2..1..2....0..2..1..2....0..2..0..1....0..0..2..0....0..1..2..1
%e ..1..0..1..0....2..0..2..1....1..2..1..2....0..2..2..1....1..2..0..2
%e ..2..1..2..0....0..1..0..1....2..0..1..0....1..2..1..1....1..0..2..0
%Y Cf. A266681.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 02 2016
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