A189179 Number of n X 2 array permutations with each element making a single king move.

1, 9, 33, 185, 913, 4777, 24577, 127385, 658801, 3410313, 17648609, 91343481, 472746833, 2446730345, 12663143361, 65538688857, 339198332209, 1755536122697, 9085854920609, 47024245778489, 243376070611729, 1259603657442857

Offset: 1

Author

R. H. Hardin, Apr 18 2011

Keywords

• nonn

Comments

Column 2 of A189186.

Examples

			Some solutions for 3 X 2:
..1..0....1..2....2..0....2..0....1..0....1..2....3..0....2..3....3..2....3..0
..3..4....5..0....4..1....3..1....4..5....0..5....5..1....0..1....0..1....4..1
..5..2....3..4....5..3....5..4....2..3....3..4....2..4....5..4....5..4....5..2
		

Links

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

Crossrefs

Cf. A189186.

Formula

Empirical: a(n) = 5*a(n-1) + 4*a(n-2) - 16*a(n-3).

Empirical g.f.: x*(1 + 4*x - 16*x^2) / (1 - 5*x - 4*x^2 + 16*x^3). - Colin Barker, Mar 01 2018