%I
%S 60,912,11664,136080,1504656,16061328,167226768,1709114256,
%T 17218688400,171498136464,1692252695952,16569199473552,
%U 161173122151824,1559011041375120,15007175850454416,143849270956794768
%N Number of n X 4 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.
%H R. H. Hardin, <a href="/A268967/b268967.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 18*a(n1)  81*a(n2) for n>3.
%F Conjectures from _Colin Barker_, Jan 17 2019: (Start)
%F G.f.: 12*x*(1  x)*(5  9*x) / (1  9*x)^2.
%F a(n) = 16*3^(2*n3) * (8*n+3) for n>1.
%F (End)
%e Some solutions for n=4:
%e ..1..0..0..0. .1..0..1..2. .2..1..0..1. .2..1..2..1. .2..1..2..1
%e ..1..0..0..1. .0..0..1..2. .0..0..0..0. .2..1..2..2. .2..1..2..2
%e ..0..1..2..0. .1..0..2..2. .1..2..1..2. .2..2..1..2. .0..0..1..2
%e ..2..1..0..0. .0..1..2..1. .1..0..1..0. .1..0..1..1. .1..2..1..2
%Y Column 4 of A268971.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 16 2016
