A208196 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 two of its immediate leftward or upward or left-upward diagonal neighbors.

5, 178, 10366, 639701, 39725054, 2468504665, 153402542384, 9533100532733, 592428713557570, 36816123505610549, 2287915709208554132, 142181136908012254369, 8835760693778126853518, 549093000211986917072609

Offset: 1

Author

R. H. Hardin, Feb 24 2012

Keywords

• nonn

Comments

Column 3 of A208201.

Examples

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

Links

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

Crossrefs

Cf. A208201.

Formula

Empirical: a(n) = 66*a(n-1) - 222*a(n-2) - 1100*a(n-3) + 363*a(n-4) + 594*a(n-5) - 216*a(n-6) for n>7.

Empirical g.f.: x*(5 - 152*x - 272*x^2 + 561*x^3 + 25*x^4 - 261*x^5 + 72*x^6) / ((1 - 6*x - 3*x^2 + 2*x^3)*(1 - 60*x - 135*x^2 + 108*x^3)). - Colin Barker, Jun 29 2018