A267625 Number of nX2 arrays containing 2 copies of 0..n-1 with every element equal to or 1 greater than any west neighbor modulo n and the upper left element equal to 0.

1, 3, 7, 27, 138, 900, 7110, 66150, 708120, 8573040, 115781400, 1725154200, 28103922000, 496799503200, 9469060801200, 193546022670000

Offset: 1

Author

R. H. Hardin, Jan 18 2016

Keywords

• nonn

Comments

Column 2 of A267629.

Examples

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

Crossrefs

Cf. A267629.