A266452 Number of nX2 arrays containing 2 copies of 0..n-1 with no element 1 greater than its north neighbor modulo n and the upper left element equal to 0.

1, 1, 5, 101, 3417, 184881, 14216101, 1477674733, 199405047857, 33889007175041, 7081268215880805, 1784184251089927605

Offset: 1

Author

R. H. Hardin, Dec 29 2015

Keywords

• nonn

Comments

Column 2 of A266455.

Examples

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

Crossrefs

Cf. A266455.