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%I #8 Jan 19 2019 12:08:35
%S 4,80,768,6224,46464,330192,2270592,15251152,100647168,655139152,
%T 4217820672,26911075152,170416738944,1072338720464,6710943646848,
%U 41800542176720,259288295447040,1602497927690832,9871915467776256
%N Number of n X 2 0..3 arrays with some element plus some horizontally, antidiagonally or vertically adjacent neighbor totalling three exactly once.
%H R. H. Hardin, <a href="/A269146/b269146.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 12*a(n-1) - 38*a(n-2) + 12*a(n-3) - a(n-4) for n>5.
%F Empirical g.f.: 4*x*(1 - x)*(1 + 9*x - x^2 - x^3) / (1 - 6*x + x^2)^2. - _Colin Barker_, Jan 19 2019
%e Some solutions for n=4:
%e ..3..2. .0..0. .2..0. .3..3. .1..0. .1..0. .1..3. .3..1. .0..2. .1..1
%e ..2..0. .2..3. .0..2. .3..3. .1..1. .0..2. .0..1. .1..0. .0..0. .3..3
%e ..1..0. .2..2. .0..3. .1..0. .1..3. .0..0. .0..0. .0..1. .2..3. .3..2
%e ..0..1. .3..3. .2..3. .0..0. .1..0. .1..3. .2..0. .0..2. .3..3. .0..2
%Y Column 2 of A269152.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 20 2016
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