A207863 Number of n X n 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).

1, 4, 2052, 455546040, 103204230192540988, 47890666906311937749901098886, 81523212441914346544073433818166292337910075, 839780322234263638551379612300530069754865868713324092842519030, 81184462760528172324981018065090176893681709356914242351556151349811667519060498973390

Offset: 1

Author

R. H. Hardin, Feb 21 2012

Keywords

• nonn

Examples

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

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..11

Crossrefs

Diagonal of A207868.

Extensions

Terms a(6) and beyond from Andrew Howroyd, Mar 11 2023