OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 20*a(n-2) + 27*a(n-3) - 14*a(n-4) - 25*a(n-5) + 4*a(n-6) + 5*a(n-7) - a(n-8).
Empirical g.f.: x*(8 + 13*x - 13*x^2 - 24*x^3 + 4*x^4 + 5*x^5 - x^6) / ((1 + x)*(1 + 2*x - x^2)*(1 - 4*x - 9*x^2 + 5*x^3 + 4*x^4 - x^5)). - Colin Barker, Sep 13 2018
EXAMPLE
Some solutions for n=4:
..1..0..1..0....1..0..0..0....1..0..0..0....1..0..0..0....1..0..0..1
..0..0..0..0....0..0..0..0....0..0..0..1....1..0..1..0....1..0..0..0
..0..0..0..0....0..0..0..1....0..0..0..0....0..0..0..1....0..0..1..0
..0..1..0..0....1..0..0..1....1..0..0..0....0..0..0..0....1..0..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 02 2013
STATUS
approved