OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-2) - 3*a(n-4) + a(n-6).
Conjectures from Colin Barker, Oct 11 2018: (Start)
G.f.: x*(9 + 11*x - 5*x^2 - 9*x^3 + 2*x^4 + 3*x^5) / ((1 - x)^3*(1 + x)^3).
a(n) = (62 - 14*(-1)^n + (50-6*(-1)^n)*n + (11+(-1)^(1+n))*n^2) / 16.
(End)
EXAMPLE
Some solutions for n=5:
..2..0....0..1....0..1....1..0....0..1....0..2....0..1....1..0....1..0....0..1
..0..2....1..0....1..0....0..2....1..0....2..0....1..0....0..1....0..1....1..0
..2..0....0..2....0..2....2..0....0..1....0..2....0..2....1..0....2..0....2..1
..0..2....2..0....2..0....1..2....1..0....2..1....2..1....0..2....0..2....1..2
..2..1....0..2....0..2....2..1....2..1....1..2....1..2....2..1....2..1....2..1
..1..2....2..1....2..0....1..2....1..2....2..1....2..1....1..2....1..2....1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 09 2013
STATUS
approved