OFFSET
1,1
COMMENTS
Column 1 of A230949.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 14*a(n-3) + a(n-4) - a(n-5).
Empirical g.f.: 2*x*(3 - x + 14*x^2 + x^3 - x^4) / (1 - 3*x - 14*x^3 - x^4 + x^5). - Colin Barker, Mar 18 2018
EXAMPLE
Some solutions for n=2:
..0..x..0..x....0..x..2..x....0..x..0..x....0..x..0..x....0..x..0..x
..x..1..x..3....x..1..x..3....x..1..x..1....x..1..x..1....x..1..x..3
..2..x..2..x....0..x..0..x....0..x..2..x....2..x..2..x....0..x..2..x
..x..3..x..1....x..3..x..3....x..3..x..1....x..3..x..1....x..1..x..1
..2..x..0..x....2..x..2..x....2..x..0..x....2..x..0..x....0..x..0..x
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 01 2013
STATUS
approved