OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 12*a(n-1) - 48*a(n-2) + 64*a(n-3) for n>6.
Conjectures from Colin Barker, Sep 20 2018: (Start)
G.f.: x^2*(4 + 13*x + 112*x^2 - 104*x^3 - 32*x^4) / (1 - 4*x)^3.
a(n) = 2^(2*n-7) * (106 - 145*n + 50*n^2) for n>3.
(End)
EXAMPLE
Some solutions for n=3:
..0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..0....0..1....0..0
..0..2....2..2....1..0....2..3....2..1....0..1....2..2....1..2....1..2....1..2
..1..1....0..0....1..2....2..2....1..3....2..3....1..2....0..0....0..0....1..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 27 2013
STATUS
approved