OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-2) + 11*a(n-3) - 2*a(n-4) + 8*a(n-5) - 4*a(n-6).
Empirical g.f.: x*(2 + 6*x + 9*x^2 + 6*x^3 + 4*x^4 - 4*x^5) / (1 - 3*x + x^2 - 11*x^3 + 2*x^4 - 8*x^5 + 4*x^6). - Colin Barker, Feb 24 2019
EXAMPLE
Some solutions for n=7:
..1..1. .1..0. .0..1. .1..0. .0..1. .1..0. .0..1. .1..0. .0..1. .1..0
..0..1. .1..1. .0..1. .1..1. .1..0. .1..1. .0..1. .1..0. .1..0. .1..1
..0..1. .0..1. .0..1. .0..1. .0..0. .0..0. .0..1. .1..0. .1..0. .0..1
..0..0. .0..0. .0..0. .1..0. .1..1. .0..0. .0..0. .1..1. .0..1. .0..1
..1..1. .1..1. .0..1. .1..0. .0..1. .1..0. .1..1. .0..0. .1..0. .0..1
..0..1. .1..0. .1..1. .1..1. .1..0. .1..0. .1..0. .1..1. .1..0. .1..0
..1..0. .0..0. .1..0. .0..0. .1..0. .1..0. .0..1. .0..1. .0..1. .1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 18 2017
STATUS
approved