%I #6 Aug 12 2016 06:54:17
%S 0,0,8,14,52,1516,7582,46338,501270,3535396,25480614,220369120,
%T 1716544860,13279246254,108919001860,873463942418,6971258302462,
%U 56716000746978,460015101808320,3726764125840338,30399952923410062
%N Number of 3Xn arrays containing n copies of 0..3-1 with every element equal to at least one vertical or antidiagonal neighbor and the top left element equal to 0.
%C Row 3 of A268159.
%H R. H. Hardin, <a href="/A268160/b268160.txt">Table of n, a(n) for n = 1..68</a>
%e Some solutions for n=4
%e ..0..1..1..2....0..0..2..2....0..1..1..2....0..0..1..2....0..1..2..2
%e ..0..1..2..0....0..1..2..1....0..1..0..2....0..1..2..1....0..1..2..0
%e ..1..2..2..0....0..1..2..1....1..0..2..2....0..2..2..1....1..1..2..0
%Y Cf. A268159.
%K nonn
%O 1,3
%A _R. H. Hardin_, Jan 27 2016