A265229 Number of n X 2 arrays containing 2 copies of 0..n-1 with no equal vertical neighbors and new values introduced sequentially from 0.

1, 2, 7, 43, 372, 4027, 51871, 773186, 13083385, 247698481, 5186925696, 119023766737, 2969884019977, 80056947698498, 2318432654628847, 71785166633148187, 2366425763631216756, 82748313392542136011

Offset: 1

Author

R. H. Hardin, Dec 06 2015

Keywords

• nonn
• more

Examples

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

Links

• Dmitry Efimov, Hafnian of two-parameter matrices, arXiv:2101.09722 [math.CO], 2021.

Crossrefs

Column 2 of A265232.