OFFSET
1,1
COMMENTS
Column 1 of A202421.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) +a(n-2) +3*a(n-3) +a(n-4).
Empirical g.f.: x*(34 + 26*x + 43*x^2 + 13*x^3) / (1 - 2*x - x^2 - 3*x^3 - x^4). - Colin Barker, May 28 2018
EXAMPLE
Some solutions for n=5:
..0..1..0....0..0..0....1..0..0....0..0..1....0..0..0....0..0..1....0..0..1
..1..0..0....0..0..1....0..1..0....1..0..0....0..0..1....0..0..0....0..0..0
..0..0..0....1..0..0....0..0..0....0..0..0....0..1..0....1..0..0....1..0..0
..0..0..1....0..0..0....1..0..0....0..0..1....0..0..0....0..0..0....0..0..0
..0..1..0....0..1..0....0..0..0....0..0..0....0..0..0....0..0..1....0..0..0
..0..0..0....0..0..0....0..0..1....0..0..0....0..1..0....1..0..0....0..1..0
..1..0..0....0..0..0....1..0..0....0..0..0....0..0..0....0..0..0....1..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 19 2011
STATUS
approved