OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = n^5 + 5*n^4 + 4*n^3 + 6*n^2 - 2*n.
Conjectures from Colin Barker, Jan 24 2019: (Start)
G.f.: 2*x*(7 + 40*x + 15*x^2 + 2*x^3 - 4*x^4) / (1 - x)^6.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.
(End)
EXAMPLE
Some solutions for n=3:
..1. .1. .2. .1. .0. .3. .2. .1. .2. .3. .1. .2. .3. .2. .0. .1
..2. .0. .1. .0. .1. .1. .1. .3. .3. .1. .3. .0. .3. .3. .2. .2
..0. .2. .2. .1. .0. .1. .0. .2. .1. .0. .1. .3. .0. .0. .3. .1
..1. .2. .3. .2. .3. .2. .0. .2. .1. .1. .3. .0. .3. .3. .2. .3
..0. .1. .2. .3. .3. .3. .1. .3. .0. .0. .0. .0. .2. .3. .3. .3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 29 2016
STATUS
approved