OFFSET
1,1
COMMENTS
Column 1 of A218056.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-2) + 2*a(n-4) + a(n-5).
Empirical g.f.: 2*x*(2 - 2*x + 2*x^2 - x^4) / (1 - 2*x - x^2 - 2*x^4 - x^5). - Colin Barker, Feb 19 2018
EXAMPLE
All solutions for n=3:
..2....0....3....2....3....2....3....2....0....1....1....1....1....3....0....0
..1....0....3....2....2....2....1....0....0....1....1....1....0....0....0....0
..1....0....3....3....2....2....1....0....2....2....3....1....0....0....1....3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 19 2012
STATUS
approved