OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 42*a(n-1) - 351*a(n-2) + 972*a(n-3) - 810*a(n-4).
Empirical g.f.: 24*x*(8 - 93*x + 279*x^2 - 270*x^3) / ((1 - 3*x)*(1 - 39*x + 234*x^2 - 270*x^3)). - Colin Barker, Oct 08 2018
EXAMPLE
Some solutions for n=2:
..0..0..1..0..1..2..1....1..2..1..0..1..2..2....2..2..1..2..2..1..0
..1..0..1..2..2..2..2....2..2..1..2..1..2..1....2..2..2..1..2..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 05 2013
STATUS
approved