OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) + a(n-2) - 16*a(n-3) - a(n-4) + 30*a(n-5) + 4*a(n-6) - 24*a(n-7) - 4*a(n-8) + 8*a(n-9).
Empirical g.f.: 2*x^2*(1 - x)*(1 + x)*(2 - x - 8*x^2 - x^3 + 6*x^4) / ((1 - 2*x)*(1 - x - 3*x^2 + 2*x^4)^2). - Colin Barker, Feb 20 2019
EXAMPLE
Some solutions for n=4:
..0..1..1..1. .0..0..0..0. .0..0..1..0. .0..1..0..0. .0..0..0..1
..0..0..0..0. .0..1..1..1. .0..1..0..1. .1..1..1..0. .0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 29 2017
STATUS
approved