OFFSET
1,2
COMMENTS
Column 3 of A206359.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 16*a(n-1) - 20*a(n-2) - 58*a(n-3) + 33*a(n-4) + 30*a(n-5) for n>6.
Empirical g.f.: x*(1 + x - 22*x^2 + 2*x^3 + 69*x^4 + 33*x^5) / ((1 - x)*(1 - 15*x + 5*x^2 + 63*x^3 + 30*x^4)). - Colin Barker, Jun 15 2018
EXAMPLE
Some solutions for n=4:
..0..1..2....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2
..2..0..1....1..0..3....1..0..3....3..2..4....1..3..4....1..2..3....2..3..1
..1..2..3....2..3..4....2..4..0....4..3..1....2..4..3....2..0..4....1..4..0
..3..4..2....3..1..2....4..1..2....2..4..3....3..0..1....3..1..2....3..0..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 06 2012
STATUS
approved