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Number of nX2 0..2 arrays with exactly floor(nX2/2) elements equal to at least one horizontal, vertical or antidiagonal neighbor, with new values introduced in row major 0..2 order
1

%I #5 Mar 09 2013 08:10:28

%S 0,6,18,136,654,3972,21778,127226,727214,4237154,24617576,144049162,

%T 843945398,4961892900,29226194746,172530718840,1020187713214,

%U 6042341555988,35837121558046,212824919490178,1265353059527832

%N Number of nX2 0..2 arrays with exactly floor(nX2/2) elements equal to at least one horizontal, vertical or antidiagonal neighbor, with new values introduced in row major 0..2 order

%C Column 2 of A222918

%H R. H. Hardin, <a href="/A222913/b222913.txt">Table of n, a(n) for n = 1..210</a>

%e Some solutions for n=3

%e ..0..0....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1

%e ..0..1....2..2....0..2....0..0....2..2....2..1....2..0....1..0....1..1....0..0

%e ..2..0....1..2....0..1....2..1....2..1....0..1....2..2....1..2....0..2....1..2

%K nonn

%O 1,2

%A _R. H. Hardin_ Mar 09 2013