OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-3) for n>5.
Empirical g.f.: x*(535 + 426*x + 610*x^2 - 1350*x^3 - 112*x^4) / (1 - 4*x^3). - Colin Barker, Dec 04 2018
EXAMPLE
Some solutions for n=4:
..3..2..2..3..2..2....0..3..0..0..3..3....1..2..0..1..1..0....0..0..2..0..0..2
..2..3..2..2..3..2....1..1..0..1..1..0....0..1..1..0..1..1....0..1..1..0..1..1
..3..3..1..3..3..0....0..1..1..0..1..1....0..2..0..0..2..0....1..0..1..1..0..1
..3..2..2..3..2..2....0..3..0..0..2..0....1..1..0..1..1..0....0..0..2..0..0..2
..2..3..2..2..3..2....1..1..0..1..1..0....0..1..1..0..1..1....0..1..1..0..1..1
..3..0..0..3..3..1....0..1..1..0..1..1....0..3..0..0..2..0....1..0..1..1..0..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 18 2014
STATUS
approved