OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/24)*n^4 + (1/12)*n^3 - (1/24)*n^2 + (23/12)*n + 2.
Conjectures from Colin Barker, Sep 16 2018: (Start)
G.f.: x*(4 - 13*x + 18*x^2 - 10*x^3 + 2*x^4) / (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>5.
(End)
EXAMPLE
Some solutions for n=4:
..0..2....0..2....0..2....1..1....0..2....0..2....0..2....0..0....0..2....0..2
..0..2....0..2....1..0....1..1....1..0....0..2....0..2....1..1....1..0....0..2
..0..2....0..2....2..1....1..1....1..0....1..0....1..0....2..2....2..1....1..0
..0..2....1..0....2..1....1..1....1..1....1..1....1..0....2..2....2..2....2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 23 2013
STATUS
approved