A189247 Number of n X 2 array permutations with each element making zero or one king moves.

2, 24, 152, 1168, 8448, 62272, 456320, 3350016, 24579584, 180376576, 1323614208, 9712930816, 71274930176, 523026923520, 3838053810176, 28164247060480, 206673697308672, 1516604287614976, 11129082140426240, 81666965136998400

Offset: 1

Author

R. H. Hardin, Apr 19 2011

Keywords

• nonn

Comments

Column 2 of A189254.

Examples

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

Links

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

Crossrefs

Cf. A189254.

Formula

Empirical: a(n) = 6*a(n-1) + 12*a(n-2) - 16*a(n-3).

Empirical g.f.: 2*x*(1 + 6*x - 8*x^2) / (1 - 6*x - 12*x^2 + 16*x^3). - Colin Barker, Mar 01 2018