OFFSET
1,1
COMMENTS
Column 3 of A221736.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 18*a(n-1) + 17*a(n-2) + 6*a(n-3) - 17*a(n-4).
Empirical g.f.: 8*x*(1 + x + 4*x^2 - 2*x^3) / (1 - 18*x - 17*x^2 - 6*x^3 + 17*x^4). - Colin Barker, Aug 10 2018
EXAMPLE
Some solutions for n=3:
..2..0..0....2..1..0....1..1..1....0..4..0....0..1..2....2..0..1....1..0..0
..0..5..0....0..2..0....0..4..0....0..1..1....1..0..2....0..2..0....2..3..1
..0..2..0....2..1..1....0..0..2....0..1..2....0..2..1....1..2..1....1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 22 2013
STATUS
approved