A187193 Number of 6-turn rook's tours on an n X n board summed over all starting positions.

0, 0, 1440, 40896, 364800, 1902240, 7197120, 21960960, 57407616, 133531200, 283488480, 559247040, 1038660480

Offset: 1

Author

R. H. Hardin, Mar 06 2011

Keywords

• nonn
• more

Examples

			Some solutions for 3X3
..0..0..1....0..0..6....3..2..1....0..0..1....0..4..5....0..0..3....0..3..2
..3..4..2....0..4..5....0..0..0....4..6..5....1..0..0....0..5..4....6..0..0
..0..5..6....2..3..1....4..5..6....3..0..2....2..3..6....1..6..2....5..4..1
		

Crossrefs

Row 6 of A187189.

Formula

Empirical: a(n) = 32*n^7 - 258*n^6 + 846*n^5 - 1426*n^4 + 1234*n^3 - 428*n^2.

Empirical G.f.: 96*x^3*(15+306*x+812*x^2+503*x^3+44*x^4)/(1-x)^8. [Colin Barker, Jan 22 2012]