OFFSET
1,2
COMMENTS
Column 1 of A210183.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 14*a(n-1) - 26*a(n-2) - 68*a(n-3) - 24*a(n-4).
Empirical g.f.: x*(1 + x)*(1 + 36*x + 20*x^2) / ((1 - 4*x - 2*x^2)*(1 - 10*x - 12*x^2)). - Colin Barker, Jul 15 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..0....0..1....0..0....0..0....0..0....0..0....0..1....0..0....0..0
..1..2....1..2....2..3....1..2....1..2....1..2....1..2....2..0....1..2....1..2
..0..1....3..1....2..0....1..3....0..1....3..1....1..3....0..1....3..2....1..3
..1..2....2..1....1..1....0..3....1..2....1..2....3..2....3..0....0..1....2..1
..3..3....0..1....2..3....3..1....0..3....0..1....0..0....2..0....0..2....2..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 18 2012
STATUS
approved