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