OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/24)*n^4 - (1/4)*n^3 + (71/24)*n^2 - (43/4)*n + 23 for n>3.
Conjectures from Colin Barker, Oct 27 2018: (Start)
G.f.: x*(3 - 9*x + 13*x^2 - 13*x^3 + 13*x^4 - 8*x^5 + x^6 + x^7) / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>8.
(End)
EXAMPLE
Some solutions for n=4:
..3..0..0..0....3..0..0..0....3..0..0..0....3..0..0..0....3..0..0..0
..2..3..0..3....2..1..0..0....3..1..3..0....3..1..3..0....2..1..0..0
..2..0..1..0....2..0..0..0....3..2..3..1....3..1..2..3....2..0..3..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 30 2014
STATUS
approved