OFFSET
1,1
COMMENTS
Diagonal of A224550.
FORMULA
Empirical: a(n) = 6*a(n-1) - 12*a(n-2) + 5*a(n-3) + 12*a(n-4) - 12*a(n-5) - 3*a(n-6) + 6*a(n-7) - a(n-9).
Empirical g.f.: 2*x*(4 - 8*x - 9*x^2 + 36*x^3 - 34*x^4 + 11*x^5 - 5*x^6 + 7*x^7 + x^8) / ((1 - x)^3*(1 - x - x^2)^3). - Colin Barker, Aug 30 2018
EXAMPLE
Some solutions for n=3:
..0..1..0..0....0..0..0..0....1..1..0..0....0..0..0..0....0..0..0..0
..0..1..0..0....0..0..0..0....0..0..0..0....0..0..0..0....1..1..1..1
..0..1..0..1....0..0..0..0....0..0..0..1....1..1..1..1....0..0..0..0
..0..1..0..1....0..1..1..1....0..0..0..1....0..0..0..0....0..1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2013
STATUS
approved