OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 10*a(n-1) - 31*a(n-2) + 24*a(n-3) + 21*a(n-4) - 18*a(n-5) - 9*a(n-6).
Empirical g.f.: 2*x*(1 - x)*(1 - 3*x)*(1 - 2*x + 3*x^2) / (1 - 5*x + 3*x^2 + 3*x^3)^2. - Colin Barker, Jan 18 2019
EXAMPLE
Some solutions for n=4:
..1..0..0. .1..0..1. .1..0..1. .0..1..1. .1..0..0. .0..1..1. .0..1..0
..1..0..0. .0..0..0. .0..0..0. .0..0..0. .0..1..0. .0..0..0. .1..0..0
..1..0..0. .0..0..0. .0..0..1. .0..0..1. .0..0..0. .0..0..0. .0..0..0
..0..1..0. .1..1..0. .0..1..0. .0..0..0. .1..0..0. .1..0..1. .1..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 17 2016
STATUS
approved