OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 8*a(n-3) for n>5.
Empirical g.f.: 4*x*(300 + 367*x + 601*x^2 - 1610*x^3 - 72*x^4) / ((1 - 2*x)*(1 + 2*x + 4*x^2)). - Colin Barker, Dec 04 2018
EXAMPLE
Some solutions for n=4:
..3..2..2..3..2..2..3..2..2....1..1..0..1..1..0..1..1..0
..3..1..3..3..1..3..3..1..3....0..1..1..0..1..1..0..1..1
..2..2..3..2..2..3..2..2..3....0..3..0..0..3..0..0..3..0
..3..2..2..3..2..2..3..2..2....1..1..0..1..1..0..1..1..0
..3..0..3..3..1..3..3..0..3....0..1..1..0..1..1..0..1..1
..2..2..3..2..2..3..2..2..3....3..3..0..0..2..0..0..2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 18 2014
STATUS
approved