OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (2/15)*n^6 - (5/8)*n^5 + (9/2)*n^4 - (55/8)*n^3 + (283/15)*n^2 - 4*n + 11.
Conjectures from Colin Barker, Sep 17 2018: (Start)
G.f.: x*(23 - 77*x + 188*x^2 - 177*x^3 + 159*x^4 - 31*x^5 + 11*x^6) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.
(End)
EXAMPLE
Some solutions for n=4.
..0..0..0..0....0..2..2..2....0..2..2..2....0..2..2..2....0..2..2..2
..0..0..0..0....1..0..2..2....0..2..2..2....1..0..2..2....1..0..2..2
..0..0..0..0....2..1..0..0....0..2..2..2....1..1..0..2....1..1..0..2
..1..1..1..1....2..1..0..0....1..0..2..2....2..1..0..0....1..1..1..0
..2..2..2..2....2..2..1..1....1..0..2..2....2..1..0..0....2..1..1..0
..2..2..2..2....2..2..2..2....1..1..0..0....2..1..0..0....2..1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 23 2013
STATUS
approved