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) + 5*a(n-3) - 18*a(n-4) - 14*a(n-5) + 3*a(n-6) + a(n-7) + a(n-8) - a(n-9).
Empirical g.f.: x*(1 + x)*(1 + 9*x - 19*x^2 - 15*x^3 + 3*x^4 + x^5 + x^6 - x^7) / (1 - 3*x - x^2 - 5*x^3 + 18*x^4 + 14*x^5 - 3*x^6 - x^7 - x^8 + x^9). - Colin Barker, Feb 22 2019
EXAMPLE
Some solutions for n=7:
..0..1..0..0. .0..0..1..1. .0..0..0..0. .0..0..1..1. .0..0..1..0
..1..0..1..0. .0..0..1..0. .0..0..0..0. .0..0..1..0. .1..1..1..0
..1..0..0..1. .0..0..0..0. .0..0..1..0. .0..0..0..0. .0..1..1..1
..1..0..1..0. .0..0..0..1. .0..1..1..0. .0..1..1..0. .0..1..0..0
..1..0..0..1. .0..0..1..1. .0..0..0..0. .1..0..0..1. .0..0..0..1
..0..1..1..0. .1..0..0..0. .1..0..0..0. .1..0..0..1. .0..0..1..1
..0..0..0..0. .1..1..0..0. .1..1..0..0. .0..1..1..0. .0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 05 2017
STATUS
approved