OFFSET
1,1
COMMENTS
Column 2 of A221590.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 22*a(n-3) + 7*a(n-4) + 4*a(n-5) for n>8.
Empirical g.f.: 2*x*(1 - 2*x - x^2 + 4*x^3 - 13*x^4 - 6*x^5 + 7*x^6 + 4*x^7) / ((1 - 4*x)*(1 + x - x^2)*(1 - 3*x - x^2)). - Colin Barker, Aug 08 2018
EXAMPLE
Some solutions for n=3:
..1..1....0..1....1..0....0..1....0..0....0..0....0..1....0..1....1..0....0..0
..0..0....1..0....0..1....0..1....1..0....0..1....0..0....0..0....1..1....0..1
..1..1....1..1....1..1....0..0....1..1....1..1....0..0....0..1....1..0....0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 20 2013
STATUS
approved