OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + 2*a(n-2) - 2*a(n-3) - 4*a(n-4) + 3*a(n-5) + a(n-6) - a(n-7) for n>11.
Empirical g.f.: x*(5 + 44*x - 38*x^2 - 122*x^3 - 72*x^4 + 141*x^5 + 97*x^6 + 11*x^7 - 106*x^8 - 4*x^9 + 36*x^10) / ((1 - x)*(1 - x - 3*x^2 - x^3 + 3*x^4 - x^6)). - Colin Barker, Feb 04 2019
EXAMPLE
Some solutions for n=4:
..0..1..2. .0..0..0. .0..0..1. .0..0..0. .0..1..0. .0..1..0. .0..0..0
..1..2..2. .1..2..1. .2..1..1. .0..1..2. .1..1..2. .0..1..2. .1..2..2
..1..2..0. .2..2..1. .2..1..2. .1..2..2. .1..2..2. .1..2..2. .1..2..1
..2..0..0. .0..0..0. .1..0..2. .1..2..0. .0..0..0. .2..2..0. .0..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 30 2016
STATUS
approved