A187192 Number of 5-turn rook's tours on an n X n board summed over all starting positions.

0, 0, 720, 9792, 58800, 231840, 705600, 1800960, 4046112, 8251200, 15594480, 27720000, 46846800, 75889632, 118591200, 179665920, 264955200, 381594240, 538190352

Offset: 1

Author

R. H. Hardin, Mar 06 2011

Keywords

• nonn
• more

Examples

			Some solutions for 3X3
..0..5..1....0..0..4....0..1..5....1..0..2....1..0..0....4..0..5....2..3..1
..0..0..2....2..0..3....0..3..4....0..5..0....2..0..5....3..0..0....0..0..0
..0..4..3....1..0..5....0..2..0....0..4..3....3..0..4....2..1..0....5..4..0
		

Crossrefs

Row 5 of A187189.

Formula

Empirical: a(n) = 16*n^6 - 98*n^5 + 228*n^4 - 238*n^3 + 92*n^2.

Empirical G.f.: 48*x^3*(15+99*x+112*x^2+14*x^3)/(1-x)^7. [Colin Barker, Jan 22 2012]