A264952 Number of nX2 arrays containing 2 copies of 0..n-1 with no equal horizontal or vertical neighbors.

0, 2, 12, 504, 22320, 1521360, 140394240, 17034433920, 2627788262400, 502511002156800, 116684130094963200, 32342603041381248000

Offset

1,2

Comments

Column 2 of A264954.

Links

Table of n, a(n) for n=1..12.

Example

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

Crossrefs

Cf. A264954.

Sequence in context: A013147 A250110 A266501 * A324790 A371202 A050643

Adjacent sequences: A264949 A264950 A264951 * A264953 A264954 A264955

Keyword

nonn

Author

R. H. Hardin, Nov 29 2015

Status

approved