OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 8*a(n-1) - 25*a(n-2) + 35*a(n-3) - 7*a(n-4) - 49*a(n-5) + 77*a(n-6) - 55*a(n-7) + 20*a(n-8) - 3*a(n-9) for n>12.
Empirical g.f.: x*(854 - 2498*x - 3033*x^2 + 21041*x^3 - 34325*x^4 + 22458*x^5 + 1073*x^6 - 9797*x^7 + 4718*x^8 - 398*x^9 - 153*x^10 + 3*x^11) / ((1 - x)^7*(1 - x - 3*x^2)). - Colin Barker, Nov 24 2018
EXAMPLE
Some solutions for n=4:
..0..1..1..3....0..2..3..3....0..1..2..3....0..0..0..3....0..2..2..2
..1..0..0..0....0..0..0..0....0..0..0..0....0..0..0..3....0..0..0..0
..1..0..0..0....2..2..2..2....1..0..0..0....2..0..0..2....0..0..0..0
..1..0..0..0....0..0..0..0....2..0..0..0....2..0..0..1....1..0..0..0
..3..0..0..0....1..1..1..1....3..1..1..0....3..0..0..1....3..2..2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 29 2014
STATUS
approved