A198909 Number of nX3 0..7 arrays with values 0..7 introduced in row major order and no element equal to any horizontal or vertical neighbor.

2, 34, 2051, 269940, 54381563, 13088156547, 3352514013159, 876632051686733, 230783525290600476, 60892298359864756053, 16078352442288906898825, 4246466444504000973551502, 1121629692628918068552449185

Offset: 1

Author

R. H. Hardin Oct 31 2011

Keywords

• nonn

Comments

Column 3 of A198914

Examples

			Some solutions with values 0 to 7 for n=4
..0..1..2....0..1..2....0..1..2....0..1..0....0..1..2....0..1..2....0..1..2
..3..4..0....3..4..5....3..0..4....2..3..4....1..3..4....3..0..4....3..4..0
..5..3..6....4..2..0....5..4..6....3..5..6....5..0..6....4..1..5....5..6..3
..0..1..7....1..6..7....6..1..7....7..4..0....0..1..7....6..7..4....3..5..7
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 431*a(n-1) -53038*a(n-2) +2570412*a(n-3) -55789402*a(n-4) [phone]*a(n-5) -3707175288*a(n-6) [phone]*a(n-7) -26380804149*a(n-8) [phone]*a(n-9) -16243626186*a(n-10) [phone]*a(n-11)