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%I #6 Aug 12 2016 06:53:59
%S 2,39,999,31501,1115170,41983402,1645807004,66428315332,2741553615797,
%T 115161107816709,4907346217889770,211619921457504517,
%U 9217713218166541066,404959978196608770290,17923299357990007812631,798420742078293208625630
%N Number of 4Xn arrays containing n copies of 0..4-1 with no element 1 greater than its north or southwest neighbor modulo 4 and the upper left element equal to 0.
%C Row 4 of A266861.
%H R. H. Hardin, <a href="/A266863/b266863.txt">Table of n, a(n) for n = 1..27</a>
%e Some solutions for n=4
%e ..0..2..1..3....0..2..2..0....0..2..3..1....0..2..3..1....0..2..3..2
%e ..2..1..1..1....0..2..1..3....0..0..1..3....0..0..1..3....0..1..3..1
%e ..2..3..3..0....0..2..3..3....0..2..3..3....2..3..1..3....2..3..1..0
%e ..0..3..2..0....3..1..1..1....2..1..1..2....0..2..1..2....1..2..0..3
%Y Cf. A266861.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 04 2016