A208051 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 or antidiagonal neighbor (colorings ignoring permutations of colors).

2, 15, 716, 83440, 18171918, 6423127757, 3376465219485, 2486327138729353, 2454996141671330713, 3143641561804718358884, 5084413934903476204054959, 10166624612435356414640715276, 24691194409056203926713355839051

Offset: 1

Author

R. H. Hardin, Feb 22 2012

Keywords

• nonn

Examples

			Some solutions for n=4
..0..1..0....0..1..0....0..1..0....0..1..0....0..1..0....0..1..0....0..1..0
..2..3..1....2..3..1....2..3..2....2..3..1....2..3..2....2..3..4....2..3..1
..0..2..0....0..4..5....0..4..0....1..0..2....0..1..4....0..5..0....4..5..3
..1..3..1....5..3..4....1..2..1....2..3..0....2..0..1....1..2..1....0..6..4
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..100 (first 20 terms from R. H. Hardin)

Crossrefs

Column 3 of A208054.

Column 6 of A216460 and column 6 of A216612.