OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-2) + 2*a(n-3) - 6*a(n-4) + 3*a(n-5) - 2*a(n-6) - a(n-7) - 2*a(n-8) + a(n-9).
Empirical g.f.: x*(1 + x - 3*x^2 - 5*x^3 + x^4 - 2*x^5 - 3*x^6 - x^7 + x^8) / ((1 - 3*x + x^2)*(1 - 2*x^3 - x^5 - x^6 - x^7)). - Colin Barker, Feb 23 2019
EXAMPLE
Some solutions for n=7:
..0..0. .0..0. .1..1. .1..1. .1..1. .1..1. .0..1. .0..0. .0..0. .1..1
..1..1. .0..0. .1..0. .1..1. .1..0. .1..1. .1..1. .0..1. .0..1. .1..0
..1..0. .1..1. .1..1. .0..0. .1..1. .0..0. .1..0. .1..1. .1..1. .0..0
..1..1. .1..0. .1..1. .0..0. .1..0. .0..1. .0..0. .0..1. .1..0. .0..1
..1..0. .1..0. .0..0. .0..0. .0..0. .1..1. .0..1. .1..1. .1..1. .1..1
..1..1. .1..1. .1..1. .1..1. .0..0. .0..1. .1..1. .0..0. .1..0. .0..1
..1..1. .1..0. .1..1. .1..1. .0..0. .1..1. .0..0. .0..0. .0..0. .1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 11 2017
STATUS
approved