A199642 Number of nX3 0..2 arrays with values 0..2 introduced in row major order and each element equal to one or two horizontal and vertical neighbors.

1, 13, 112, 1265, 12748, 134748, 1396083, 14584050, 151837464, 1582988477, 16494233432, 171904221068, 1791430664487, 18669394073270, 194560012081184, 2027588187779377, 21130256645906468, 220206564513115724

Offset: 1

Author

R. H. Hardin Nov 08 2011

Keywords

• nonn

Comments

Column 3 of A199647

Examples

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

Links

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

Formula

Empirical: a(n) = 7*a(n-1) +41*a(n-2) -44*a(n-3) -111*a(n-4) -140*a(n-5) +291*a(n-6) -225*a(n-7) +511*a(n-8) +2150*a(n-9) -3007*a(n-10) -6248*a(n-11) -624*a(n-12) +19900*a(n-13) -14308*a(n-14) +15248*a(n-15) -13312*a(n-16) -1648*a(n-17) +21440*a(n-18) -5632*a(n-19) -3968*a(n-20) +5632*a(n-21) -14336*a(n-22) -8192*a(n-23) for n>24