OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-2) + 7*a(n-4) + a(n-5) + 2*a(n-6) + a(n-7) - a(n-8) + a(n-9) for n>10.
Empirical g.f.: x*(36 + 49*x + 37*x^2 + 111*x^3 - 34*x^4 + 31*x^5 - 12*x^6 - 18*x^7 + 25*x^8 - 10*x^9) / (1 - 2*x^2 - 7*x^4 - x^5 - 2*x^6 - x^7 + x^8 - x^9). - Colin Barker, Dec 27 2018
EXAMPLE
Some solutions for n=4:
..1..0..1....0..1..0....0..0..1....0..0..0....0..0..0....0..0..0....1..0..1
..0..1..0....1..0..1....0..1..0....0..0..1....0..0..0....0..0..1....0..1..0
..1..0..1....0..1..0....1..0..1....0..1..0....1..0..1....0..1..0....1..0..1
..0..1..0....0..0..1....0..1..0....0..0..1....0..1..0....0..0..1....0..0..0
..1..0..1....0..0..0....0..0..1....0..0..0....1..0..1....0..1..0....0..0..1
..0..0..0....1..0..1....0..1..0....0..0..1....0..0..0....1..0..1....0..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 13 2015
STATUS
approved