OFFSET
1,1
COMMENTS
Column 3 of A208501.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-2) + 4*a(n-3) + 2*a(n-4) + 2*a(n-5) - 2*a(n-6) + a(n-7) + a(n-9) for n>11.
Empirical g.f.: 2*x*(3 + 18*x + 27*x^2 + 33*x^3 + 9*x^4 + 3*x^5 - 11*x^6 + 12*x^7 + 2*x^8 + 6*x^9 - 2*x^10) / (1 - x^2 - 4*x^3 - 2*x^4 - 2*x^5 + 2*x^6 - x^7 - x^9). - Colin Barker, Mar 06 2018
EXAMPLE
Some solutions for n=4:
..0..1..1....1..0..1....0..1..1....0..1..1....0..1..0....1..0..0....0..1..0
..0..1..1....1..1..1....0..1..1....1..0..0....0..1..1....0..1..1....1..1..0
..1..0..0....0..1..0....1..0..0....1..1..0....1..0..1....0..1..1....1..0..1
..1..0..0....1..0..1....1..1..1....0..1..1....1..1..0....1..0..0....0..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 27 2012
STATUS
approved