OFFSET
1,1
COMMENTS
Column 2 of A251950
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 20*a(n-3) -120*a(n-6) +231*a(n-9) -249*a(n-12) +198*a(n-15) -134*a(n-18) +55*a(n-21) for n>27
EXAMPLE
Some solutions for n=4
..3..2..2..3....3..2..0..0....0..1..1..0....2..0..3..2....0..1..1..0
..1..3..3..1....1..0..1..1....2..3..0..2....0..1..1..3....3..1..1..3
..3..0..0..3....1..3..1..1....0..1..1..0....0..1..1..0....2..0..0..2
..3..0..0..3....0..2..0..0....3..1..1..0....2..0..0..2....0..1..1..0
..1..3..3..1....1..0..1..1....2..3..0..2....0..1..1..3....3..1..1..0
..1..2..0..3....1..0..1..1....2..1..2..0....0..1..1..0....2..0..0..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 11 2014
STATUS
approved