OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + a(n-4) - 3*a(n-5) + 3*a(n-6) - a(n-7) for n>12.
Empirical g.f.: x*(480 - 111*x - 163*x^2 + 109*x^3 - 849*x^4 + 441*x^5 + 245*x^6 - 309*x^7 + 214*x^8 - 230*x^9 + 88*x^10 + 108*x^11) / ((1 - x)^4*(1 + x)*(1 + x^2)). - Colin Barker, Dec 22 2018
EXAMPLE
Some solutions for n=4:
..1..0..0..0..0....1..0..0..1..1....0..0..0..1..1....0..1..1..1..1
..0..0..0..0..0....1..0..0..0..0....0..0..0..0..0....0..0..0..0..0
..1..1..0..0..1....1..0..0..0..1....1..0..0..0..1....1..1..1..1..1
..1..0..0..1..1....0..0..0..0..1....0..0..0..1..1....0..0..0..0..0
..1..1..1..1..1....1..1..0..0..1....1..1..1..1..1....1..1..1..1..1
..1..1..0..0..1....1..0..0..0..1....0..0..0..0..1....1..1..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 03 2015
STATUS
approved