OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + 2*a(n-2) + a(n-3) + 6*a(n-4) - 14*a(n-5) - 4*a(n-6) + 2*a(n-7) - 4*a(n-8) + 4*a(n-9) for n>10.
Empirical g.f.: x*(60 + 50*x + 89*x^2 + 9*x^3 - 514*x^4 - 66*x^5 + 34*x^6 - 90*x^7 + 144*x^8 - 12*x^9) / ((1 + x - x^2)*(1 - 3*x + 2*x^2 - 6*x^3 + 2*x^4 + 6*x^5 + 4*x^7)). - Colin Barker, Dec 27 2018
EXAMPLE
Some solutions for n=4:
..0..1..0..0....0..0..0..0....0..0..1..0....0..0..0..0....1..0..0..0
..1..0..0..0....0..0..0..0....0..0..0..1....1..0..0..0....0..0..0..1
..0..0..0..0....1..0..0..1....0..0..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..0..1
..1..0..0..1....0..0..0..1....0..0..1..0....0..0..0..0....0..0..0..0
..0..0..0..0....1..0..0..0....0..0..0..1....0..0..1..0....1..0..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 10 2015
STATUS
approved