OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 3*a(n-3) + 3*a(n-4) + 3*a(n-5) + 3*a(n-6) - 2*a(n-8) - a(n-9).
Empirical g.f.: x*(4 + 2*x + 10*x^2 + 11*x^3 + 12*x^4 + 9*x^5 - 2*x^6 - 7*x^7 - 3*x^8) / ((1 + x^2 - x^3)*(1 + x^2 + x^3)*(1 - x - 2*x^2 - x^3)). - Colin Barker, Oct 01 2018
EXAMPLE
Some solutions for n=7:
..0..0..0..1..0..0..1..0....0..0..0..1..1..0..0..0....0..0..0..1..0..0..0..0
..1..0..0..0..0..0..0..1....0..0..0..0..0..1..0..0....1..0..0..0..1..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 16 2013
STATUS
approved