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Number of 2 X n nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal, diagonal or antidiagonal neighbor (colorings ignoring permutations of colors).
2

%I #12 May 07 2014 05:21:17

%S 2,4,30,377,7239,193228,6752442,296290708,15835464207,1007305486325,

%T 74890158775564,6413015600048526,624933541074620780,

%U 68603269124243415049,8411144435499643711885,1143251056778815843116186

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

%C Row 2 of A208096.

%H R. H. Hardin, <a href="/A208097/b208097.txt">Table of n, a(n) for n = 1..19</a>

%e Some solutions for n=4:

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

%e ..3..1..4..5....0..1..0..2....0..1..3..1....0..1..2..0....3..1..2..4

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 23 2012