OFFSET
1,3
COMMENTS
Row 7 of A187507.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..50
FORMULA
Empirical: a(n) = 285*n^2 - 1624*n + 2210 for n>5.
Conjectures from Colin Barker, Apr 24 2018: (Start)
G.f.: x^3*(1 + x)*(20 + 250*x + 44*x^2 - 20*x^3 - 9*x^4) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>8.
(End)
EXAMPLE
Some solutions for 4 X 4:
..0..0..0..0....1..2..0..0....0..5..3..1....0..0..1..2....4..5..6..0
..0..7..0..0....0..3..4..0....0..6..4..2....0..7..5..3....2..3..7..0
..1..5..6..0....0..7..5..0....0..7..0..0....0..0..6..4....0..1..0..0
..2..3..4..0....0..0..6..0....0..0..0..0....0..0..0..0....0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 10 2011
STATUS
approved