OFFSET
1,3
COMMENTS
Row 9 of A187586.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..50
FORMULA
Empirical: a(n) = 30966*n^2 - 251630*n + 489234 for n>7.
Conjectures from Colin Barker, Apr 24 2018: (Start)
G.f.: x^3*(13 + 2753*x + 18915*x^2 + 29715*x^3 + 16432*x^4 - 286*x^5 - 3976*x^6 - 1634*x^7) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>10.
(End)
EXAMPLE
Some solutions for 4 X 4:
..0..0..7..8....3..0..0..9....0..0..8..9....6..8..9..0....0..4..0..0
..5..6..0..9....4..2..8..0....0..1..6..7....7..5..0..0....0..5..3..1
..2..4..0..0....5..7..1..0....0..2..4..5....4..2..0..0....8..6..0..2
..3..1..0..0....6..0..0..0....0..3..0..0....0..3..1..0....9..7..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 11 2011
STATUS
approved