OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 16*a(n-1) -60*a(n-2) -47*a(n-3) +92*a(n-4) +448*a(n-5) +448*a(n-6) +256*a(n-7) for n>9.
Empirical g.f.: 2*x*(8 - 47*x - 81*x^2 + 61*x^3 + 656*x^4 + 939*x^5 + 468*x^6 - 112*x^7 - 64*x^8) / (1 - 16*x + 60*x^2 + 47*x^3 - 92*x^4 - 448*x^5 - 448*x^6 - 256*x^7). - Colin Barker, Oct 04 2018
EXAMPLE
Some solutions for n=4:
..0..1..2..0..1..2....2..1..2..0..1..2....2..1..2..1..0..2....2..0..1..2..0..2
..2..0..1..2..1..2....2..0..1..2..1..2....2..1..0..1..0..2....1..2..0..1..0..2
..1..2..1..2..0..1....1..2..1..0..1..2....0..1..2..1..0..1....0..1..2..1..0..2
..1..2..0..1..2..1....1..2..1..0..1..0....0..1..0..1..2..1....2..1..2..1..0..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 22 2013
STATUS
approved