A189429 Number of n X 3 array permutations with each element not moving, or moving one space N, SW or SE.

1, 3, 9, 31, 109, 367, 1245, 4247, 14453, 49167, 167325, 569447, 1937829, 6594495, 22441517, 76369751, 259890293, 884421039, 3009733885, 10242290119, 34855077573, 118613751711, 403649138125, 1373640273207, 4674573594645

Offset

1,2

Comments

Column 3 of A189435.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = a(n-1) +4*a(n-2) +10*a(n-3) +12*a(n-4) +8*a(n-5).

Empirical g.f.: x*(1 + 2*x + 2*x^2) / (1 - x - 4*x^2 - 10*x^3 - 12*x^4 - 8*x^5). - Colin Barker, May 02 2018

Example

Some solutions for 4 X 3:
..0..4..5....0..4..5....0..1..2....3..1..2....0..4..2....0..4..5....0..1..2
..6..2..1....1..2..8....3..7..5....6..0..5....1..7..5....3..2..1....3..4..5
..9..3..8....6..3.11....6.10..4....4.10.11....6..3..8....6..7..8....9.10..8
..7.10.11....9.10..7....9..8.11....9..8..7....9.10.11....9.10.11....7..6.11

Crossrefs

Cf. A189435.

Sequence in context: A279971 A127927 A148967 * A123222 A148968 A148969

Adjacent sequences: A189426 A189427 A189428 * A189430 A189431 A189432

Keyword

nonn

Author

R. H. Hardin, Apr 22 2011

Status

approved