OFFSET
1,3
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) - a(n-2) + 2*a(n-3) - a(n-4) for n>6.
Empirical g.f.: x*(1 - x)*(1 + x^2)^2 / (1 - 2*x + x^2 - 2*x^3 + x^4). - Colin Barker, Feb 26 2019
EXAMPLE
Some solutions for n=5:
..0..1..1..0..0. .0..0..0..0..0. .0..0..0..0..0. .0..1..1..0..0
..1..1..0..1..1. .0..0..1..1..0. .0..0..0..0..0. .1..1..0..0..0
..0..0..1..1..0. .0..1..1..0..0. .0..0..0..0..0. .0..0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 27 2017
STATUS
approved