OFFSET
1,3
COMMENTS
Row 6 of A187507.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..50
FORMULA
Empirical: a(n) = 123*n^2 - 600*n + 697 for n>4.
Conjectures from Colin Barker, Apr 24 2018: (Start)
G.f.: x^3*(36 + 164*x + 64*x^2 - 11*x^3 - 7*x^4) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>7.
(End)
EXAMPLE
Some solutions for 4 X 4:
..0..0..0..0....1..2..0..0....0..0..2..0....0..0..6..0....0..0..6..0
..5..3..0..0....0..3..0..0....0..0..3..1....0..0..4..5....0..0..4..5
..6..4..2..0....6..4..0..0....0..0..4..5....0..0..2..3....0..1..2..3
..0..0..0..1....0..5..0..0....0..0..0..6....0..0..0..1....0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 10 2011
STATUS
approved