OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 4*a(n-2) + 3*a(n-3) + a(n-4) + 4*a(n-5) - a(n-6) - 6*a(n-7) - a(n-8) + a(n-9).
Empirical g.f.: x*(4 + 7*x + 4*x^2 + 3*x^3 + 3*x^4 - 6*x^5 - 7*x^6 + x^8) / (1 - x - 4*x^2 - 3*x^3 - x^4 - 4*x^5 + x^6 + 6*x^7 + x^8 - x^9). - Colin Barker, Feb 23 2019
EXAMPLE
Some solutions for n=5:
..0..0. .1..0. .1..0. .0..0. .0..1. .1..1. .0..1. .0..0. .1..0. .0..1
..0..0. .0..0. .0..0. .0..0. .0..1. .0..0. .1..0. .1..1. .0..0. .0..1
..0..0. .0..1. .1..0. .1..0. .0..0. .1..1. .0..1. .0..0. .1..0. .1..1
..0..0. .0..0. .0..0. .1..0. .0..0. .0..0. .1..0. .1..0. .0..1. .1..0
..0..1. .0..0. .1..0. .0..0. .1..1. .0..0. .0..0. .0..0. .0..1. .1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 15 2017
STATUS
approved