OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + 7*a(n-2) + 8*a(n-3) for n>5.
Empirical g.f.: x*(8 + 5*x - 13*x^2 - 28*x^3 - 4*x^4) / (1 - 2*x - 7*x^2 - 8*x^3). - Colin Barker, Feb 01 2019
EXAMPLE
Some solutions for n=4:
..0..0..0..1. .0..0..0..1. .0..1..1..1. .0..1..1..1. .0..0..0..1
..2..2..2..2. .1..2..2..0. .2..0..0..0. .2..2..0..0. .1..2..2..0
..1..1..1..1. .0..1..1..2. .1..1..2..2. .1..1..2..2. .0..1..1..2
..0..0..0..0. .2..2..0..0. .0..0..1..1. .0..0..0..1. .2..0..0..0
..2..2..2..2. .0..1..2..2. .1..2..2..0. .2..2..2..0. .1..2..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 19 2016
STATUS
approved