A265229 Number of nX2 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

1,2

Comments

Column 2 of A265232.

Links

Table of n, a(n) for n=1..18.

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

Example

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

Crossrefs

Cf. A265232.

Sequence in context: A144059 A352293 A078676 * A286684 A086331 A121418

Adjacent sequences: A265226 A265227 A265228 * A265230 A265231 A265232

Keyword

nonn

Author

R. H. Hardin, Dec 06 2015

Status

approved