OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 19*a(n-1) - 45*a(n-2) + 27*a(n-3) for n>5.
Empirical g.f.: x*(10 - 68*x + 117*x^2 - 81*x^3 + 27*x^4) / ((1 - x)*(1 - 18*x + 27*x^2)). - Colin Barker, Oct 07 2018
EXAMPLE
Some solutions for n=4:
..0..1..0..2....0..1..1..3....0..1..3..1....0..1..3..2....0..1..0..2
..1..0..0..0....1..1..3..3....0..1..3..3....1..3..2..3....0..0..0..0
..1..0..0..2....1..3..3..2....3..3..1..1....3..3..3..2....1..0..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 03 2013
STATUS
approved