OFFSET
1,1
COMMENTS
Column 2 of A210413.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 31*a(n-1) + 40*a(n-2) - 280*a(n-3) + 96*a(n-4).
Empirical g.f.: 2*x*(39 + 51*x - 372*x^2 + 128*x^3) / (1 - 31*x - 40*x^2 + 280*x^3 - 96*x^4). - Colin Barker, Jul 15 2018
EXAMPLE
Some solutions for n=4:
..0..0..1....0..0..0....0..0..0....0..1..0....0..0..0....0..0..0....0..0..0
..1..2..0....1..2..1....1..2..3....2..1..2....1..2..3....1..2..1....1..2..1
..0..1..2....3..2..3....0..1..2....1..0..3....3..2..1....2..3..0....1..0..0
..0..3..3....1..3..0....1..3..0....2..3..1....1..0..3....1..3..1....1..2..3
..0..1..0....2..1..1....0..1..3....0..0..2....3..0..1....3..0..1....3..0..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 21 2012
STATUS
approved