OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = n^7 + 7*n^6 + 16*n^5 - 12*n^4 - 5*n^3 + 18*n^2 - 15*n + 4.
Conjectures from Colin Barker, Jan 25 2019: (Start)
G.f.: 2*x*(7 + 395*x + 1684*x^2 + 608*x^3 - 321*x^4 + 143*x^5 + 6*x^6 - 2*x^7) / (1 - x)^8.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.
(End)
EXAMPLE
Some solutions for n=4:
..1. .4. .2. .0. .2. .1. .4. .3. .1. .3. .4. .2. .4. .3. .3. .2
..4. .1. .0. .3. .4. .3. .2. .0. .3. .4. .1. .1. .1. .1. .4. .3
..0. .3. .3. .1. .1. .0. .4. .3. .1. .4. .4. .4. .0. .1. .2. .0
..1. .2. .2. .2. .1. .4. .0. .0. .0. .3. .2. .1. .3. .0. .4. .2
..1. .0. .0. .3. .3. .2. .1. .2. .2. .1. .2. .3. .4. .3. .3. .3
..4. .1. .3. .2. .3. .3. .4. .0. .1. .1. .4. .3. .4. .0. .2. .1
..4. .3. .1. .1. .2. .2. .0. .3. .1. .3. .1. .0. .3. .3. .1. .4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 01 2016
STATUS
approved