A221251 Number of nX4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2.

4, 81, 2116, 58081, 1612900, 44903401, 1250753956, 34842328921, 970622980804, 27039303204489, 753252725702500, 20983889126032561, 584562920742585316, 16284579460194091201, 453650957002812576484, 12637673040690140943889

Offset: 1

Author

R. H. Hardin Jan 06 2013

Keywords

• nonn

Comments

Column 4 of A221255

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..23

Formula

Empirical: a(n) = 39*a(n-1) -356*a(n-2) +1365*a(n-3) -2739*a(n-4) +2904*a(n-5) -1683*a(n-6) +573*a(n-7) -116*a(n-8) +15*a(n-9) -a(n-10)