OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 10*a(n-1) - 14*a(n-2) + 37*a(n-3) - 65*a(n-4) + 70*a(n-5) - 76*a(n-6) + 74*a(n-7) - 32*a(n-8).
Empirical g.f.: x^2*(4 + 7*x - 19*x^2 + 13*x^3 - 4*x^4 + 9*x^5 - 8*x^6) / (1 - 10*x + 14*x^2 - 37*x^3 + 65*x^4 - 70*x^5 + 76*x^6 - 74*x^7 + 32*x^8). - Colin Barker, Feb 09 2019
EXAMPLE
Some solutions for n=4:
..0..2. .0..3. .0..2. .0..3. .0..1. .0..2. .0..2. .0..3. .0..0. .0..3
..1..3. .1..2. .1..3. .1..2. .0..2. .1..3. .1..3. .1..2. .1..3. .1..2
..3..0. .3..0. .0..2. .0..2. .3..2. .2..3. .2..2. .1..3. .2..1. .1..1
..2..2. .2..1. .3..3. .3..3. .1..1. .0..1. .0..1. .0..2. .0..3. .0..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 16 2016
STATUS
approved