OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 18*a(n-2) + 16*a(n-3) + 12*a(n-4) - 12*a(n-5).
Empirical g.f.: 3*x*(27 + 111*x + 92*x^2 + 56*x^3 - 64*x^4) / (1 - x - 18*x^2 - 16*x^3 - 12*x^4 + 12*x^5). - Colin Barker, Oct 20 2018
EXAMPLE
Some solutions for n=5:
..0..2....2..2....0..1....1..2....0..0....2..1....2..1....2..1....1..1....0..0
..1..1....2..0....1..1....0..0....0..1....0..2....0..2....2..2....0..0....2..2
..0..1....0..1....0..2....0..2....2..2....2..2....2..0....2..2....2..0....1..0
..2..2....1..1....2..2....1..2....2..2....1..1....0..1....2..1....1..0....1..0
..0..0....1..2....1..2....1..2....1..2....1..0....1..0....1..0....1..1....2..0
..0..0....1..0....0..1....2..0....0..1....1..2....2..2....0..0....2..0....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 19 2014
STATUS
approved