A200796 Number of nX3 0..3 arrays with values 0..3 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors.

5, 178, 9880, 583813, 34679839, 2060918000, 122478253815, 7278777317468, 432571571252989, 25707362563355693, 1527766813187552208, 90793889493222901029, 5395804057415427972197, 320668071260622898796015

Offset: 1

Author

R. H. Hardin Nov 22 2011

Keywords

• nonn

Comments

Column 3 of A200801

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 60*a(n-1) -17*a(n-2) -964*a(n-3) -2509*a(n-4) +968*a(n-5) +23125*a(n-6) +31652*a(n-7) -4566*a(n-8) -17118*a(n-9) -29646*a(n-10) -74826*a(n-11) -64125*a(n-12) -13932*a(n-13) +4131*a(n-14) +1458*a(n-15) for n>16