OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 4*a(n-2) - 3*a(n-3) - 2*a(n-4) - 6*a(n-5) + 3*a(n-6) - a(n-7) + a(n-9).
Empirical g.f.: x*(5 + 4*x - 5*x^2 - 7*x^3 - 4*x^4 + 2*x^5 - x^6 + x^7 + x^8) / (1 - 3*x - 4*x^2 + 3*x^3 + 2*x^4 + 6*x^5 - 3*x^6 + x^7 - x^9). - Colin Barker, Feb 22 2019
EXAMPLE
Some solutions for n=7:
..0..0..0. .0..1..1. .0..0..0. .1..0..1. .0..0..0. .0..0..1. .0..0..0
..1..0..0. .0..1..1. .0..0..1. .0..0..0. .0..0..0. .0..0..0. .1..0..1
..0..0..0. .1..0..0. .0..0..0. .1..0..0. .0..1..1. .1..0..1. .0..0..0
..1..0..0. .0..1..0. .0..1..0. .0..1..0. .0..1..1. .0..0..0. .1..0..0
..0..0..1. .1..0..0. .0..0..1. .1..0..0. .0..0..0. .0..0..1. .0..1..1
..0..0..0. .0..0..1. .1..0..0. .0..1..0. .1..0..1. .0..0..0. .0..1..1
..1..0..1. .0..0..0. .0..0..1. .1..0..1. .0..0..0. .0..0..1. .0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 13 2017
STATUS
approved