OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = n^6 + 6*n^5 + 15*n^4 + 14*n^3 + 3*n^2 + 3*n.
Conjectures from Colin Barker, Jan 25 2019: (Start)
G.f.: 2*x*(21 + 166*x + 158*x^2 + 17*x^4 - 2*x^5) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.
(End)
EXAMPLE
Some solutions for n=3:
..1. .3. .3. .1. .2. .0. .1. .2. .2. .0. .3. .2. .2. .0. .2. .2
..1. .0. .3. .0. .2. .0. .1. .3. .2. .0. .2. .0. .1. .3. .1. .0
..1. .2. .0. .0. .2. .2. .2. .0. .0. .0. .0. .3. .0. .2. .0. .2
..2. .0. .1. .3. .2. .0. .3. .1. .2. .2. .1. .3. .0. .2. .2. .0
..1. .0. .2. .0. .0. .3. .0. .1. .0. .2. .0. .1. .1. .0. .1. .1
..3. .1. .2. .1. .2. .2. .0. .1. .3. .0. .2. .3. .2. .0. .2. .3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 02 2016
STATUS
approved