OFFSET
1,1
COMMENTS
Column 1 of A239858.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-2) +2*a(n-3).
Empirical g.f.: 2*x*(1 + x + x^2) / (1 - x^2 - 2*x^3). - Colin Barker, Feb 18 2018
EXAMPLE
All solutions for n=4:
..3....3....2....2....2....3
..2....2....3....3....3....2
..3....3....3....2....3....2
..2....3....3....2....2....2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 28 2014
STATUS
approved