A209021 Number of n X 2 1..5 arrays with every element value z a city block distance of exactly z from another element value z.

1, 2, 16, 152, 1721, 21083, 217825, 2135214, 20752645, 208916566, 2138876698

Offset

1,2

Comments

Column 2 of A209023.

Links

Table of n, a(n) for n=1..11.

Example

Some solutions for n=6
..4..3....4..3....3..1....4..2....3..2....2..2....5..5....2..5....1..4....4..1
..5..4....3..5....3..1....2..3....3..3....4..2....2..1....4..4....1..1....1..1
..3..1....4..2....2..3....3..2....2..2....4..2....3..1....2..1....1..4....1..2
..1..1....2..3....2..3....3..3....3..2....2..2....2..2....1..1....1..2....2..4
..4..2....4..2....2..2....4..3....3..1....2..4....5..3....5..4....1..4....2..2
..2..5....5..4....1..1....3..3....1..1....4..4....5..2....4..4....4..2....2..2

Crossrefs

Cf. A209023.

Sequence in context: A290785 A209391 A259901 * A209056 A209213 A012391

Adjacent sequences: A209018 A209019 A209020 * A209022 A209023 A209024

Keyword

nonn

Author

R. H. Hardin, Mar 04 2012

Status

approved