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%I #9 Mar 11 2023 20:15:13
%S 2,34,2052,278982,68162042,26419793726,15002771641712,
%T 11807624578397830,12361734324171045410,16679505289611340233906,
%U 28284296659644702241447604,59055088260515144420128767278,149249218670114328150978145481610
%N Number of n X 3 nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal or vertical neighbor (colorings ignoring permutations of colors).
%H Andrew Howroyd, <a href="/A207865/b207865.txt">Table of n, a(n) for n = 1..190</a> (terms 1..20 from R. H. Hardin)
%e Some solutions for n=5
%e ..0..1..2....0..1..0....0..1..0....0..1..0....0..1..0....0..1..0....0..1..0
%e ..2..0..1....1..0..1....1..0..1....1..0..1....1..0..2....1..0..1....1..2..1
%e ..0..1..0....0..1..0....0..1..0....0..1..0....0..1..3....0..1..0....2..0..2
%e ..1..0..1....1..0..1....1..0..1....1..2..1....1..0..1....2..0..1....0..1..0
%e ..0..1..0....0..2..0....2..1..0....0..1..0....0..1..2....0..1..0....1..0..1
%Y Column 3 of A207868.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 21 2012
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