OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) - 13*a(n-2) - 35*a(n-3).
Conjectures from Colin Barker, Jan 26 2019: (Start)
G.f.: 6*x*(1 - 3*x - 6*x^2) / ((1 - 5*x)*(1 - 4*x - 7*x^2)).
a(n) = (-924*5^n + (660-195*sqrt(11))*(2-sqrt(11))^n + 15*(2+sqrt(11))^n*(44+13*sqrt(11))) / 385.
(End)
EXAMPLE
Some solutions for n=6:
..5. .1. .0. .0. .3. .1. .1. .5. .3. .0. .5. .1. .5. .1. .1. .4
..2. .0. .5. .5. .0. .1. .4. .3. .1. .3. .4. .4. .4. .4. .0. .3
..4. .3. .5. .0. .4. .5. .2. .3. .1. .3. .1. .5. .2. .5. .3. .5
..5. .1. .0. .2. .3. .1. .0. .5. .5. .5. .2. .3. .2. .1. .2. .3
..2. .4. .4. .4. .2. .2. .2. .0. .0. .2. .5. .5. .4. .0. .5. .1
..3. .4. .4. .3. .3. .5. .0. .3. .2. .0. .2. .3. .2. .1. .2. .2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 03 2016
STATUS
approved