OFFSET
1,1
COMMENTS
Column 2 of A205361.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 15*a(n-1) - 76*a(n-2) + 146*a(n-3) - 84*a(n-4).
Empirical g.f.: x*(50 - 475*x + 1237*x^2 - 882*x^3) / ((1 - x)*(1 - 6*x)*(1 - 8*x + 14*x^2)). - Colin Barker, Jun 11 2018
EXAMPLE
Some solutions for n=4:
..0..0..0....0..0..1....0..1..2....0..1..2....0..0..0....0..1..0....0..1..1
..1..0..1....2..2..1....0..1..0....2..0..1....0..0..0....2..1..2....2..2..2
..2..1..2....1..0..1....0..2..2....0..0..0....0..0..0....2..1..2....1..1..1
..1..0..1....2..0..1....1..1..0....2..0..1....0..0..0....0..1..2....0..2..2
..0..2..0....1..0..2....2..2..2....1..2..0....0..0..0....0..1..2....0..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 26 2012
STATUS
approved