OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + a(n-2) + a(n-3) + 2*a(n-4) - 2*a(n-5) + 2*a(n-6) - 4*a(n-7) - 3*a(n-8) + 2*a(n-9) - 4*a(n-10) + 2*a(n-11) for n>12.
Empirical g.f.: x*(49 + 38*x + 31*x^2 - 4*x^3 - 87*x^4 - 20*x^5 - 162*x^6 - 67*x^7 + x^8 - 96*x^9 + 78*x^10 - 6*x^11) / (1 - x - x^2 - x^3 - 2*x^4 + 2*x^5 - 2*x^6 + 4*x^7 + 3*x^8 - 2*x^9 + 4*x^10 - 2*x^11). - Colin Barker, Dec 27 2018
EXAMPLE
Some solutions for n=4:
..0..0..0..0....0..0..1..0....0..0..0..1....0..1..0..0....0..0..0..1
..0..1..0..0....0..0..0..1....1..0..0..0....1..0..0..0....0..0..0..0
..1..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....1..0..0..1
..0..0..0..0....1..0..0..0....1..0..0..1....0..0..0..1....0..0..0..0
..1..0..0..1....0..0..0..1....0..0..0..0....0..0..1..0....0..0..0..0
..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....1..0..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 04 2015
STATUS
approved