OFFSET
1,3
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + 5*a(n-2) +2*a(n-3) - 17*a(n-4) - 24*a(n-5) - 16*a(n-6).
Empirical g.f.: 8*x^3 / (1 - x - 3*x^2 - 4*x^3)^2. - Colin Barker, Feb 21 2019
EXAMPLE
Some solutions for n=4:
..0..1. .1..0. .0..0. .0..0. .0..0. .0..0. .1..0. .1..0. .0..0. .0..1
..1..0. .0..1. .1..0. .0..1. .0..1. .1..0. .1..0. .0..1. .1..0. .1..0
..1..0. .1..0. .0..1. .1..0. .1..0. .1..0. .1..0. .0..1. .0..1. .0..1
..0..0. .0..0. .0..1. .1..0. .0..1. .1..0. .0..0. .0..0. .1..0. .0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 21 2017
STATUS
approved