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 A207993 Number of n X n 0..2 arrays with new values 0..2 introduced in row major order and no element equal to any horizontal or vertical neighbor (colorings ignoring permutations of colors). 3

%I

%S 1,3,41,1302,96831,16932816,6978332618,6787438272198,

%T 15595829208171337,84713253582265127190,1088296274542436098185362,

%U 33079232010276428576508643620,2379573338713223879592059518246838

%N Number of n X n 0..2 arrays with new values 0..2 introduced in row major order and no element equal to any horizontal or vertical neighbor (colorings ignoring permutations of colors).

%C Diagonal of A207997.

%H R. H. Hardin, <a href="/A207993/b207993.txt">Table of n, a(n) for n = 1..16</a>

%e Some solutions for n=4

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

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

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

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

%t A207997 = Import["https://oeis.org/A207997/b207997.txt", "Table"][[All, 2]];

%t a[n_] := A207997[[2 n^2 - 2 n + 1]];

%t Table[a[n], {n, 1, 16}] (* _Jean-François Alcover_, Sep 23 2019 *)

%K nonn

%O 1,2

%A _R. H. Hardin_, Feb 22 2012

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Last modified September 24 21:05 EDT 2021. Contains 347651 sequences. (Running on oeis4.)