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%I #4 Feb 16 2016 13:49:26
%S 81,1728,15552,136080,1125360,9093528,72081792,563173128,4349328912,
%T 33272350344,252534743280,1904015932416,14274182767248,
%U 106487231224248,791006745522096,5853579437553624,43172409083833728,317460508504648992
%N Number of 4Xn 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.
%C Row 4 of A268971.
%H R. H. Hardin, <a href="/A268974/b268974.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 18*a(n-1) -111*a(n-2) +282*a(n-3) -333*a(n-4) +180*a(n-5) -36*a(n-6) for n>12
%e Some solutions for n=4
%e ..2..1..0..0. .0..0..1..2. .0..1..0..0. .2..1..0..0. .0..1..2..1
%e ..0..0..1..2. .0..2..1..2. .0..0..0..0. .0..0..0..0. .2..1..0..0
%e ..1..2..2..2. .1..0..1..0. .2..1..0..0. .1..0..1..1. .0..0..1..2
%e ..2..1..0..0. .0..0..0..0. .2..1..0..1. .1..0..0..0. .1..0..0..0
%Y Cf. A268971.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 16 2016
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