OFFSET
1,3
COMMENTS
Column 1 of A183729.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 8*a(n-1) - 11*a(n-2) - 23*a(n-3) + 6*a(n-4) + 7*a(n-5) - 2*a(n-6).
Empirical g.f.: x^2*(1 + 2*x - x^2)^2 / ((1 + x)*(1 - 5*x + 2*x^2)*(1 - 4*x - 2*x^2 + x^3)). - Colin Barker, Apr 04 2018
EXAMPLE
All solutions with the first block increasing clockwise for 3 X 2:
..3..4....1..2....4..5....2..3....5..0....0..1
..2..5....0..3....3..0....1..4....4..1....5..2
..1..0....5..4....2..1....0..5....3..2....4..3
...
...R.......R.......R.......R.......R.......R...
...R.......R.......R.......R.......R.......R...
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 06 2011
STATUS
approved