OFFSET
1,1
COMMENTS
Column 4 of A185567.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 217*a(n-1) - 1371*a(n-2) + 2835*a(n-3) - 2025*a(n-4).
Empirical g.f.: 4*x*(16 - 97*x + 201*x^2 - 135*x^3) / (1 - 217*x + 1371*x^2 - 2835*x^3 + 2025*x^4). - Colin Barker, Apr 16 2018
EXAMPLE
Some solutions for 3 X 4 with a(1,1)=0:
..0..0..2..0....0..0..3..0....0..2..0..2....0..0..3..1....0..2..2..0
..0..2..0..3....2..0..3..2....0..2..0..2....2..2..2..2....0..2..0..2
..0..3..3..2....2..2..1..2....2..3..2..1....0..3..0..0....0..2..3..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 31 2011
STATUS
approved