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) + 30*a(n-3) - 9*a(n-4).
Empirical g.f.: 2*x*(1 - 2*x)*(1 - x + x^2) / (1 - 5*x + 3*x^2)^2. - Colin Barker, Jan 15 2019
EXAMPLE
Some solutions for n=4:
..0..1..0. .0..0..0. .1..0..0. .0..1..0. .0..1..1. .1..0..1. .1..0..0
..0..1..0. .0..1..0. .1..1..0. .0..1..0. .0..0..0. .0..0..0. .1..0..0
..1..0..0. .0..0..1. .0..0..1. .1..0..0. .1..0..0. .1..1..0. .1..1..0
..0..0..1. .0..1..0. .1..0..0. .1..0..1. .1..0..0. .0..0..0. .0..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 15 2016
STATUS
approved