OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (8/3)*n^3 - 18*n^2 + (145/3)*n - 42 for n>2.
Conjectures from Colin Barker, Dec 07 2018: (Start)
G.f.: x*(2 - 3*x + 5*x^2 + 4*x^3 + 7*x^4 + x^5) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>6.
(End)
EXAMPLE
Some solutions for n=4:
..0..0....0..1....0..0....0..0....0..0....0..0....0..1....0..1....0..0....0..0
..1..1....1..1....1..1....1..1....0..1....0..1....0..1....0..1....0..0....0..0
..1..1....2..2....2..2....1..2....1..1....0..1....0..1....0..1....0..1....0..0
..1..1....2..2....3..3....2..2....2..2....1..1....0..1....1..1....0..1....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 24 2014
STATUS
approved