OFFSET
1,2
COMMENTS
Column 4 of A298167.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-2) - a(n-3) - 2*a(n-4) - 2*a(n-5) + a(n-6) + a(n-7).
Empirical g.f.: x^2*(2 - 2*x - 2*x^2 - 2*x^3 + x^4 + 2*x^5) / ((1 - x - x^2)*(1 - x - x^2 - x^3 + x^5)). - Colin Barker, Mar 23 2018
EXAMPLE
Some solutions for n=8:
..0..0..0..0. .0..0..0..0. .0..0..1..1. .0..0..1..1. .0..0..0..0
..0..0..0..0. .0..0..0..0. .0..0..1..1. .0..0..1..1. .0..0..0..0
..1..1..1..1. .0..0..0..0. .0..0..1..1. .0..0..1..1. .0..0..0..0
..1..1..1..1. .1..1..1..1. .0..1..0..1. .0..0..1..1. .0..0..0..0
..1..1..1..1. .1..1..1..1. .1..0..1..0. .0..0..1..1. .1..1..1..1
..1..1..1..1. .1..1..1..1. .1..1..0..0. .0..0..1..1. .1..1..1..1
..0..0..0..0. .0..0..0..0. .1..1..0..0. .1..1..0..0. .0..0..0..0
..0..0..0..0. .0..0..0..0. .1..1..0..0. .1..1..0..0. .0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 14 2018
STATUS
approved