OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-2) + 4*a(n-3) + 6*a(n-4) - a(n-5) - 5*a(n-6) - 5*a(n-7) + 2*a(n-9) - a(n-10) for n>12.
Empirical g.f.: 9*x*(191 + 144*x + 27*x^2 - 510*x^3 - 1162*x^4 - 433*x^5 + 395*x^6 + 733*x^7 + 170*x^8 - 284*x^9 + 63*x^10 + 26*x^11) / ((1 - x)*(1 + x)*(1 + x + x^2)*(1 - x - 3*x^3 - 3*x^4 + 3*x^5 - x^6)). - Colin Barker, Dec 07 2018
EXAMPLE
Some solutions for n=4:
..0..1..0..0..2..2....0..0..1..1..2..2....0..0..1..1..2..1....0..1..0..0..2..0
..0..0..1..1..2..1....2..1..1..0..1..0....0..2..0..2..2..1....2..2..0..0..1..1
..2..1..1..0..0..2....2..0..0..1..1..2....2..0..0..1..1..2....2..1..2..1..2..1
..2..0..0..1..0..1....1..1..0..1..0..0....2..0..2..2..1..2....1..2..2..1..1..0
..1..1..0..0..2..2....1..1..2..2..0..0....1..1..2..2..0..0....1..2..1..2..2..0
..1..1..2..1..2..2....0..2..2..1..2..1....1..0..1..0..1..0....0..0..2..2..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 23 2014
STATUS
approved