OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) + 22*a(n-2) - 56*a(n-3) - 120*a(n-4) + 32*a(n-5) + 64*a(n-6).
Empirical g.f.: 4*x*(24 + 23*x - 416*x^2 - 588*x^3 + 240*x^4 + 352*x^5) / ((1 - 4*x - 8*x^2)*(1 - 14*x^2 + 8*x^4)). - Colin Barker, Oct 12 2018
EXAMPLE
Some solutions for n=5:
..1..2....3..2....1..4....1..4....2..3....1..2....0..3....4..1....3..2....2..1
..3..0....3..0....2..3....2..1....0..3....4..1....1..0....2..1....1..4....4..1
..2..1....2..1....0..3....0..3....0..1....1..2....2..3....3..4....4..3....2..1
..0..3....0..3....1..0....1..0....3..2....1..4....0..3....4..1....1..2....3..0
..2..3....2..3....2..3....0..3....4..1....4..3....0..1....3..2....3..0....1..2
..1..4....0..3....0..3....2..3....3..2....4..1....0..3....0..3....1..0....3..4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 19 2013
STATUS
approved