OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 21*a(n-1) - 124*a(n-2) - 72*a(n-3) + 2128*a(n-4) - 432*a(n-5) - 12608*a(n-6) - 10752*a(n-7).
Empirical g.f.: x*(473 - 6668*x + 11784*x^2 + 132224*x^3 - 178736*x^4 - 1110848*x^5 - 870912*x^6) / ((1 + 2*x)*(1 - 6*x)*(1 - 8*x)*(1 - 6*x - 8*x^2)*(1 - 3*x - 14*x^2)). - Colin Barker, Oct 20 2018
EXAMPLE
Some solutions for n=4:
..0..1..2..0....1..2..1..1....0..2..1..0....1..0..2..2....1..1..0..1
..0..1..2..0....2..1..0..0....1..1..2..1....2..1..1..1....0..2..1..2
..2..1..0..2....2..1..0..0....2..0..1..2....1..2..2..2....0..2..1..0
..1..2..1..1....0..1..0..0....0..2..1..0....2..1..1..1....1..1..0..1
..2..1..0..2....1..0..1..1....1..1..0..1....1..2..0..0....2..2..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 16 2014
STATUS
approved