OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + 11*a(n-3) - 18*a(n-4) + 4*a(n-5).
Empirical g.f.: x*(1 + 2*x - 3*x^2 - 14*x^3 + 4*x^4) / (1 - 4*x + 5*x^2 - 11*x^3 + 18*x^4 - 4*x^5). - Colin Barker, Feb 25 2019
EXAMPLE
Some solutions for n=5:
..1..1. .1..1. .1..1. .1..0. .1..1. .0..0. .1..1. .0..0. .1..1. .0..0
..0..1. .0..1. .1..0. .1..1. .1..1. .0..0. .1..1. .0..0. .0..1. .1..1
..0..0. .0..1. .0..0. .0..0. .1..1. .0..0. .0..0. .0..0. .0..0. .1..1
..1..1. .1..1. .1..1. .1..1. .0..0. .1..1. .1..1. .0..0. .1..1. .0..0
..1..0. .0..1. .0..1. .1..1. .0..0. .1..1. .0..1. .0..0. .1..1. .0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 22 2017
STATUS
approved