OFFSET
1,3
COMMENTS
Row 6 of A187857.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..50
FORMULA
Empirical: a(n) = 28294*n^2 - 224508*n + 433614 for n>9.
Conjectures from Colin Barker, Apr 26 2018: (Start)
G.f.: x^3*(846 + 7394*x + 20704*x^2 + 11461*x^3 + 17172*x^4 - 3232*x^5 + 10073*x^6 - 8800*x^7 + 3655*x^8 - 2685*x^9) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>12.
(End)
EXAMPLE
Some solutions for 4 X 4:
..0..0..0..0....5..0..6..0....0..3..2..6....0..0..1..0....0..0..0..1
..3..2..4..0....4..3..0..0....1..0..0..5....0..5..0..0....0..0..3..0
..0..1..0..0....0..0..2..0....0..0..0..4....3..2..4..0....6..5..2..0
..6..5..0..0....1..0..0..0....0..0..0..0....6..0..0..0....0..0..4..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 14 2011
STATUS
approved