OFFSET
1,1
COMMENTS
Column 3 of A258730.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) -6*a(n-2) +20*a(n-3) -34*a(n-4) +24*a(n-5) -16*a(n-6) +8*a(n-7) -a(n-8).
Empirical g.f.: x*(190 - 152*x + 736*x^2 - 1712*x^3 + 1215*x^4 - 836*x^5 + 464*x^6 - 60*x^7) / (1 - 4*x + 6*x^2 - 20*x^3 + 34*x^4 - 24*x^5 + 16*x^6 - 8*x^7 + x^8). - Colin Barker, Jan 26 2018
EXAMPLE
Some solutions for n=4:
..2....0....2....0....1....0....0....2....3....0....3....1....0....0....1....0
..2....0....2....2....2....1....3....1....3....2....2....2....0....3....0....3
..0....3....0....2....2....0....0....2....1....0....3....2....1....1....1....0
..0....0....1....1....3....2....1....2....1....0....3....3....2....2....3....1
..2....0....1....3....0....3....1....2....2....1....3....2....3....2....3....1
..2....2....0....3....2....0....1....2....3....0....3....2....0....2....3....0
..2....1....2....0....3....0....0....3....2....0....0....2....3....0....0....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 08 2015
STATUS
approved