OFFSET
1,3
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]
EXAMPLE
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
KEYWORD
nonn,more
AUTHOR
R. H. Hardin, Mar 06 2011
STATUS
approved