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%I #6 Aug 12 2016 06:53:59
%S 6,72,1304,31501,843874,24244702,728850883,22663306978,723210750621,
%T 23536767146485,778080992727147,26055452315387786,881920582298144042,
%U 30122404974018012719,1036868581470252969758,35932758405637296245430
%N Number of 4Xn arrays containing n copies of 0..4-1 with no element 1 greater than its west or northeast neighbor modulo 4 and the upper left element equal to 0.
%C Row 4 of A266867.
%H R. H. Hardin, <a href="/A266869/b266869.txt">Table of n, a(n) for n = 1..20</a>
%e Some solutions for n=4
%e ..0..0..2..0....0..3..2..2....0..3..1..1....0..2..0..0....0..0..2..0
%e ..2..1..3..2....3..2..1..3....2..1..3..2....1..3..2..1....2..0..3..3
%e ..1..1..1..0....1..1..1..0....3..2..2..0....3..2..1..1....2..1..3..2
%e ..3..3..3..2....0..3..2..0....0..0..3..1....2..0..3..3....1..3..1..1
%Y Cf. A266867.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 04 2016