OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 25*a(n-1) - 90*a(n-2) + 81*a(n-3).
Empirical g.f.: 24*x*(4 - 19*x + 18*x^2) / (1 - 25*x + 90*x^2 - 81*x^3). - Colin Barker, Oct 08 2018
EXAMPLE
Some solutions for n=3:
..0..0..1..2..2..2....1..0..1..2..2..1....0..1..0..1..2..1....2..1..0..1..2..2
..0..0..1..2..1..0....1..2..2..2..2..2....2..1..0..1..2..1....2..1..2..1..2..2
..1..0..1..0..1..2....1..2..1..2..2..1....0..1..2..1..2..2....2..2..2..2..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 05 2013
STATUS
approved