OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 7*a(n-3) + 2*a(n-4) + 6*a(n-5) + 14*a(n-6) - 20*a(n-7) - 4*a(n-8) + 8*a(n-9) for n>10.
Empirical g.f.: x*(148 - 388*x - 386*x^2 + 1315*x^3 + 63*x^4 + 173*x^5 - 2930*x^6 + 1444*x^7 + 1192*x^8 - 608*x^9) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 2*x^3)). - Colin Barker, Dec 05 2018
EXAMPLE
Some solutions for n=4:
..0..1..1..2..2....0..0..1..0..0....0..0..1..1..0....0..0..1..1..0
..1..1..2..2..0....1..1..2..1..1....2..2..3..3..2....2..3..2..3..2
..1..2..2..0..0....1..1..2..1..1....0..0..1..1..0....2..3..2..3..2
..2..2..0..0..1....0..0..1..0..0....2..2..3..3..0....0..1..0..1..0
..2..0..0..1..1....1..1..2..1..1....0..0..1..1..2....0..1..0..1..0
..0..0..1..1..2....1..1..2..1..1....2..2..3..3..0....3..2..3..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 20 2014
STATUS
approved