OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 2*a(n-2) + 6*a(n-3) + 5*a(n-4) + a(n-5) - 2*a(n-6) - 2*a(n-7) - a(n-8) for n>9.
Empirical g.f.: 2*x*(65 + 71*x + 145*x^2 + 72*x^3 - 26*x^4 - 79*x^5 - 52*x^6 - 16*x^7 + 7*x^8) / (1 - x - 2*x^2 - 6*x^3 - 5*x^4 - x^5 + 2*x^6 + 2*x^7 + x^8). - Colin Barker, Dec 03 2018
EXAMPLE
Some solutions for n=4:
..0..0..0..0....1..0..0..0....3..2..3..3....0..1..0..0....3..3..2..3
..0..0..1..0....0..0..1..0....2..3..3..2....0..0..0..0....3..3..3..2
..0..0..0..0....0..0..0..0....3..3..3..3....1..0..0..0....3..3..3..3
..0..1..0..0....0..0..0..0....3..3..3..3....0..0..0..0....3..3..3..3
..0..0..0..1....0..0..0..0....3..3..2..3....0..0..0..0....3..3..3..2
..1..0..0..0....0..1..0..0....2..3..3..3....0..0..0..0....2..3..3..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 16 2014
STATUS
approved