OFFSET
1,3
COMMENTS
Row 4 of A187296.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..50
FORMULA
Empirical: a(n) = 58*n^2 - 232*n + 180 for n>5.
Conjectures from Colin Barker, Apr 23 2018: (Start)
G.f.: 2*x^3*(27 + 17*x + 27*x^2 - 15*x^3 + 7*x^4 - 5*x^5) / (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:
..1..0..0..0....0..0..0..0....0..0..1..0....0..0..0..0....0..0..0..0
..0..0..0..0....0..0..0..0....0..0..0..0....0..2..1..0....2..4..3..0
..2..4..3..0....1..3..2..4....4..3..2..0....0..4..0..0....1..0..0..0
..0..0..0..0....0..0..0..0....0..0..0..0....0..3..0..0....0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 08 2011
STATUS
approved