A189603 Number of n X n array permutations with each element not moving, or moving one space E, S or NW.

1, 3, 20, 464, 30283, 5897476, 3394457868, 5778059258273, 29117129479453520, 434446215594380010575

Offset

1,2

Comments

Diagonal of A189610.

Links

Table of n, a(n) for n=1..10.

Example

Some solutions for 3 X 3
..4..1..2....0..1..2....4..0..2....4..0..1....4..0..2....0..1..2....4..1..2
..0..8..5....3..8..4....7..1..5....7..8..2....3..1..5....7..8..4....0..3..5
..3..6..7....6..7..5....3..6..8....3..6..5....6..7..8....3..6..5....6..7..8

Crossrefs

Cf. A189610.

Sequence in context: A322455 A138897 A365365 * A203228 A174972 A300917

Adjacent sequences: A189600 A189601 A189602 * A189604 A189605 A189606

Keyword

nonn

Author

R. H. Hardin, Apr 24 2011

Status

approved