A232155 Number of n X 2 0..3 arrays with every 0 next to a 1, every 1 next to a 2 and every 2 next to a 3 horizontally, vertically or antidiagonally, and no adjacent values equal.

2, 18, 62, 218, 746, 2600, 9004, 31262, 108492, 376566, 1307146, 4537292, 15750222, 54673186, 189786782, 658806476, 2286917482, 7938591212, 27557292770, 95659868830, 332064969492, 1152700237642, 4001379292082, 13890026339060

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) + 2*a(n-2) - 13*a(n-3) - 5*a(n-4) + 14*a(n-5) - 3*a(n-6) + 3*a(n-7) + 8*a(n-8) + a(n-9) - a(n-10) for n>11.

Empirical g.f.: 2*x*(1 + 5*x - 7*x^2 - 20*x^3 - 3*x^4 + 24*x^5 + 5*x^6 + 7*x^7 + 15*x^8 + 2*x^9 - 2*x^10) / (1 - 4*x - 2*x^2 + 13*x^3 + 5*x^4 - 14*x^5 + 3*x^6 - 3*x^7 - 8*x^8 - x^9 + x^10). - Colin Barker, Oct 03 2018

Example

Some solutions for n=7:
..2..1....2..3....3..1....0..3....1..3....0..1....0..1....2..1....3..0....1..2
..3..0....0..1....0..2....1..2....2..1....2..3....3..2....3..2....1..3....0..3
..2..3....2..3....3..1....3..0....3..0....1..2....0..1....1..0....2..0....1..0
..1..2....0..1....2..0....2..1....1..2....0..3....3..2....3..2....1..3....2..1
..3..1....2..3....3..1....3..2....3..1....1..0....1..3....0..1....2..1....3..0
..2..0....1..2....0..2....1..0....2..3....2..3....2..1....3..2....3..0....1..2
..3..2....0..3....1..3....2..3....1..0....1..2....3..2....0..1....2..1....3..1

Crossrefs

Column 2 of A232161.

Sequence in context: A119118 A213820 A078837 * A368755 A112365 A242200

Adjacent sequences: A232152 A232153 A232154 * A232156 A232157 A232158

Keyword

nonn

Author

R. H. Hardin, Nov 19 2013

Status

approved