OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 12*a(n-1) - 30*a(n-2) - 36*a(n-3).
Empirical g.f.: 7*x*(1 - 5*x - 5*x^2) / ((1 - 6*x)*(1 - 6*x - 6*x^2)). - Colin Barker, Jan 29 2019
EXAMPLE
Some solutions for n=6:
..5. .1. .2. .3. .0. .4. .4. .6. .0. .1. .1. .5. .5. .0. .2. .5
..2. .1. .0. .3. .4. .3. .0. .0. .5. .1. .2. .4. .2. .0. .3. .1
..2. .0. .6. .0. .1. .0. .4. .2. .5. .2. .4. .0. .6. .3. .0. .2
..2. .0. .5. .4. .2. .3. .5. .6. .2. .0. .0. .4. .5. .6. .1. .3
..4. .6. .1. .3. .6. .1. .1. .2. .0. .6. .0. .6. .0. .2. .3. .0
..2. .2. .6. .0. .2. .5. .6. .1. .0. .2. .2. .2. .0. .2. .5. .0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 04 2016
STATUS
approved