OFFSET
1,2
COMMENTS
Column 2 of A231785.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) -8*a(n-2) +2*a(n-3) +3*a(n-4) -a(n-5) for n>6.
Empirical g.f.: x*(1 + 11*x - 20*x^2 + 5*x^3 + 8*x^4 - 2*x^5) / (1 - 6*x + 8*x^2 - 2*x^3 - 3*x^4 + x^5). - Colin Barker, Mar 18 2018
EXAMPLE
Some solutions for n=7:
..0..2....0..1....0..1....0..0....0..0....0..1....0..0....0..2....0..0....0..1
..0..2....0..1....0..0....0..0....1..1....0..2....0..0....2..2....1..0....0..1
..2..2....2..1....1..2....2..2....2..1....2..2....1..2....2..2....2..2....0..1
..2..0....1..1....0..2....2..2....0..0....2..0....0..2....2..2....2..2....0..1
..1..0....1..1....2..2....0..1....0..0....2..1....0..2....0..0....0..0....2..1
..0..0....0..2....2..2....2..1....1..0....0..0....1..2....1..0....0..0....2..0
..2..2....0..2....0..2....2..1....1..2....1..0....1..2....2..0....2..2....1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 13 2013
STATUS
approved