A189436 Number of 4 X n array permutations with each element not moving, or moving one space N, SW or SE.

1, 9, 31, 140, 571, 2413, 10069, 42205, 176624, 739573, 3096173, 12962845, 54270579, 227212636, 951259751, 3982596009, 16673747193, 69807202249, 292258553696, 1223585260409, 5122727328297, 21447083573633, 89791504401207

Offset: 1

Author

R. H. Hardin, Apr 22 2011

Keywords

• nonn

Comments

Row 4 of A189435.

Examples

			Some solutions for 4 X 3:
..0..1..5....0..1..2....0..4..5....3..4..2....0..4..5....0..4..5....0..4..5
..6..2..8....3..4..5....3..2..1....1..0..5....3..2..1....6..2..1....1..2..8
..4..3.11....9.10..8....9.10..8....6..7..8....6.10.11....9..3..8....6..3.11
..9.10..7....7..6.11....7..6.11....9.10.11....9..8..7....7.10.11....9.10..7
		

Links

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

Crossrefs

Cf. A189435.

Formula

Empirical: a(n) = 4*a(n-1) +2*a(n-2) -6*a(n-3) +4*a(n-4) -a(n-5).

Empirical g.f.: x*(1 + 5*x - 7*x^2 + 4*x^3 - x^4) / (1 - 4*x - 2*x^2 + 6*x^3 - 4*x^4 + x^5). - Colin Barker, May 02 2018