OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 10*a(n-1) - 37*a(n-2) + 65*a(n-3) - 51*a(n-4) + 2*a(n-5) + 20*a(n-6) - 10*a(n-7) + 4*a(n-8) for n>11.
Empirical g.f.: 2*x^2*(4 - 21*x + 34*x^2 - 51*x^4 + 32*x^5 + 16*x^6 - 10*x^7 + x^8 - x^9) / ((1 - 2*x)*(1 - 8*x + 21*x^2 - 23*x^3 + 5*x^4 + 8*x^5 - 4*x^6 + 2*x^7)). - Colin Barker, Sep 22 2018
EXAMPLE
Some solutions for n=4:
..0..2..1....0..1..0....0..1..0....0..3..2....0..2..1....0..1..3....0..1..3
..1..3..2....2..3..2....3..2..1....1..0..1....1..3..0....3..2..0....3..2..0
..2..0..1....1..0..3....1..0..3....2..3..2....0..1..2....0..1..2....1..3..1
..1..3..2....3..1..2....3..2..1....1..0..1....3..0..3....3..0..3....0..2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 01 2013
STATUS
approved