OFFSET
1,1
COMMENTS
Column 2 of A267735.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 6*a(n-2) - 19*a(n-3) + 24*a(n-4) + 24*a(n-5) - 19*a(n-6) - 6*a(n-7) + 6*a(n-8) - a(n-9).
Empirical g.f.: x*(4 - 8*x - 8*x^2 + 13*x^3 + 26*x^4 - 17*x^5 - 7*x^6 + 6*x^7 - x^8) / ((1 + x)^3*(1 - 3*x + x^2)^3). - Colin Barker, Mar 21 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..1....0..1....1..0....1..1....0..0....1..1....0..0....1..1....0..1
..1..0....0..0....0..1....0..0....1..1....1..0....0..0....0..0....1..1....1..0
..0..0....1..0....0..1....1..1....0..1....0..1....1..1....0..0....0..0....1..1
..0..1....1..0....1..1....0..0....1..0....0..1....1..0....1..0....1..1....1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 20 2016
STATUS
approved