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%I #6 Jan 16 2024 09:34:00
%S 4,29,153,818,4386,23516,126162,676988,3632880,19495940,104627364,
%T 561499304,3013389264,16171937024,86789899608,465775377536,
%U 2499677308656,13415022525008,71994427701360,386372643782240,2073546883713888
%N Number of n X 3 0..1 arrays with every element equal to 0, 1, 2 or 3 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
%C Column 3 of A302265.
%H R. H. Hardin, <a href="/A302260/b302260.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 6*a(n-1) -2*a(n-2) +2*a(n-3) -54*a(n-4) +16*a(n-5) for n>6.
%e Some solutions for n=5
%e ..0..0..1. .0..0..1. .0..1..1. .0..1..0. .0..0..1. .0..1..0. .0..1..0
%e ..1..0..1. .0..0..1. .1..0..1. .0..1..0. .0..1..0. .1..1..1. .1..0..1
%e ..1..0..0. .1..1..0. .1..0..0. .1..0..1. .1..0..1. .0..1..1. .1..0..1
%e ..1..0..1. .1..1..0. .0..0..1. .1..1..0. .0..0..1. .0..1..0. .1..0..0
%e ..1..0..1. .0..0..1. .1..0..1. .0..1..0. .1..1..0. .1..0..1. .1..0..0
%Y Cf. A302265.
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 04 2018
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