OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 15*a(n-1) + 40*a(n-2) + 22*a(n-3) - 60*a(n-4) - 40*a(n-5) - 21*a(n-6) + 45*a(n-7).
Empirical g.f.: x*(2 - 3*x - 24*x^2 - 59*x^3 - 52*x^4 - 11*x^5 + 72*x^6) / ((1 - x)*(1 + x + x^2)*(1 - 15*x - 40*x^2 - 21*x^3 + 45*x^4)). - Colin Barker, Oct 29 2018
EXAMPLE
Some solutions for n=4:
..0..1..0....0..1..0....0..1..2....0..1..2....0..1..0....0..1..2....0..1..0
..2..3..1....1..2..3....3..0..3....1..0..3....2..0..2....3..2..1....2..3..1
..0..1..3....0..0..1....1..2..0....2..2..0....0..1..3....2..0..3....0..1..2
..1..0..2....0..0..3....3..1..2....2..2..1....2..3..0....3..1..2....1..2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2014
STATUS
approved