OFFSET
1,1
COMMENTS
Column 2 of A207100.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-4) - a(n-6) - a(n-9).
Empirical g.f.: x*(3 + 2*x^3 - x^5 - x^8) / ((1 - x)*(1 - x - x^2 - x^3 - 2*x^4 - 2*x^5 - x^6 - x^7 - x^8)). - Colin Barker, Jun 18 2018
EXAMPLE
Some solutions for n=5:
..1....0....1....0....0....0....0....0....1....0....1....1....0....0....0....0
..2....1....2....1....1....0....0....2....1....0....2....2....1....1....0....0
..2....1....1....1....2....0....2....2....2....0....1....2....2....2....0....0
..1....2....1....2....2....0....2....1....2....1....0....1....1....1....0....0
..2....2....2....0....1....1....2....2....2....2....1....0....2....0....0....2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 15 2012
STATUS
approved