A208859 Number of n X 3 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or left-upward diagonal neighbors.

5, 127, 5796, 273049, 12883280, 607924387, 28686344276, 1353633375649, 63874412830520, 3014066220322507, 142225889552418956, 6711267165754821049, 316687117317930292160, 14943635501046735026227, 705151014286332805949636

Offset: 1

Author

R. H. Hardin, Mar 02 2012

Keywords

• nonn

Comments

Column 3 of A208864.

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Cf. A208864.

Formula

Empirical: a(n) = 59*a(n-1) - 603*a(n-2) + 2211*a(n-3) - 2826*a(n-4) + 720*a(n-5) for n>6.

Empirical g.f.: x*(5 - 168*x + 1318*x^2 - 3389*x^3 + 1710*x^4 - 240*x^5) / ((1 - 2*x)*(1 - 57*x + 489*x^2 - 1233*x^3 + 360*x^4)). - Colin Barker, Jul 07 2018