A183353 One quarter the number of n X n 1..4 arrays with no two neighbors of any element equal to each other.

1, 36, 432, 3600, 24192, 147456, 829440, 4460544, 23003136, 115605504, 566231040, 2727346176, 12910067712

Offset: 1

Author

R. H. Hardin Jan 04 2011

Keywords

• nonn

Comments

Diagonal of A183362

Examples

			Some solutions for 5X5 with a(1,1)=1
..1..3..2..2..4....1..2..3..1..4....1..3..3..2..2....1..1..3..4..2
..2..4..1..3..4....1..4..3..2..4....1..2..4..4..3....3..2..2..4..1
..3..4..1..3..2....3..4..1..2..3....3..2..1..1..3....4..4..1..3..3
..1..2..2..4..1....2..2..1..4..3....4..4..3..2..4....2..3..1..2..2
..4..3..3..4..1....1..3..3..4..1....1..1..3..2..1....1..3..4..4..1