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%I #6 Aug 12 2016 06:54:00
%S 6,8,21,137,759,4835,31591,216460,1516047,10864196,79437844,590119523,
%T 4453596825,34028591249,263304258843,2058154419091,16252842542358,
%U 129434331448080,1039407597863960,8405943746368118,68447035142972923
%N Number of 4Xn arrays containing n copies of 0..4-1 with every element equal to or 1 greater than any northeast or northwest neighbors modulo 4 and the upper left element equal to 0.
%C Row 4 of A267019.
%H R. H. Hardin, <a href="/A267023/b267023.txt">Table of n, a(n) for n = 1..23</a>
%e Some solutions for n=4
%e ..0..1..3..1....0..2..0..2....0..2..0..2....0..2..0..2....0..1..3..1
%e ..2..0..2..0....3..1..3..1....2..0..3..1....3..1..3..1....2..0..2..0
%e ..1..3..1..3....1..0..2..3....1..3..1..3....1..3..1..3....0..2..1..3
%e ..0..2..3..2....1..2..0..3....0..1..3..2....0..2..0..2....3..1..3..2
%Y Cf. A267019.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 09 2016