A221324 Number of n X 4 arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2.

17, 866, 46105, 2460824, 131347807, 7010554450, 374176705928, 19970973695923, 1065911268786396, 56890876705125765, 3036435876484206258, 162063633563069131638, 8649818983278197229631, 461666606875092805859284

Offset: 1

Author

R. H. Hardin, Jan 11 2013

Keywords

• nonn

Comments

Column 4 of A221328.

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..118

Formula

Empirical: a(n) = 91*a(n-1) -2497*a(n-2) +29072*a(n-3) -168762*a(n-4) +513070*a(n-5) -765950*a(n-6) +359339*a(n-7) +283374*a(n-8) -252113*a(n-9) -12688*a(n-10) +38079*a(n-11) -6354*a(n-12) +289*a(n-13).