A221329 Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2.

1, 17, 119, 866, 6328, 46211, 337274, 2460918, 17953576, 130970758, 955393448, 6969190236, 50836821440, 370827923908, 2704988609708, 19731401249156, 143929610463264, 1049886222652688, 7658333144969252, 55863255070913284

Offset: 1

Author

R. H. Hardin, Jan 11 2013

Keywords

• nonn

Comments

Row 2 of A221328.

Examples

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

Links

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

Crossrefs

Cf. A221328.

Formula

Empirical: a(n) = 11*a(n-1) - 27*a(n-2) - a(n-3) + 8*a(n-4) - 16*a(n-5) - 6*a(n-6) + 2*a(n-7) for n>9.

Empirical g.f.: x*(1 + 6*x - 41*x^2 + 17*x^3 + 24*x^4 - 16*x^5 + x^6 + 5*x^7 - x^8) / (1 - 11*x + 27*x^2 + x^3 - 8*x^4 + 16*x^5 + 6*x^6 - 2*x^7). - Colin Barker, Aug 05 2018