A208018 - OEIS

%I #10 Jun 25 2017 17:13:12

%S 2,7,270,27093,5252041,1688298227,819147302097,562766251199622,

%T 522687453434959180,633631710314384052082,975235769907492737264795,

%U 1863659976446678796423595540,4341202639797991970260869847084,12137362722177750192276998364963783

%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, vertical, diagonal or antidiagonal neighbor (colorings ignoring permutations of colors).

%H Andrew Howroyd, <a href="/A208018/b208018.txt">Table of n, a(n) for n = 1..100</a>

%e Some solutions for n=4

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

%e ..2..3..2....2..3..2....2..3..2....2..3..0....2..3..2....2..3..4....2..3..2

%e ..4..0..4....0..1..0....4..1..0....4..5..4....0..1..0....5..6..0....0..1..0

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

%Y Column 3 of A208021.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 22 2012

%E Terms a(14) and beyond from _Andrew Howroyd_, Jun 25 2017