OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 62*a(n-1) - 969*a(n-2) + 4568*a(n-3) - 5740*a(n-4).
Conjectures from Colin Barker, Jan 11 2019: (Start)
G.f.: x*(1 - 46*x + 399*x^2 - 674*x^3) / ((1 - 2*x)*(1 - 5*x)*(1 - 14*x)*(1 - 41*x)).
a(n) = (38745*2^n + 127428*5^n + 17425*2^(2+n)*7^n + 9800*41^n) / 2092230.
(End)
EXAMPLE
Some solutions for n=4:
..0..0..0..0..0....0..0..0..0..0....0..0..0..0..0....0..0..0..0..0
..0..1..1..1..0....0..0..0..1..1....0..1..1..0..1....0..1..1..0..1
..0..0..0..1..0....0..0..1..2..0....0..0..0..0..1....0..0..0..1..2
..0..1..0..2..0....0..1..2..0..2....0..1..2..0..0....0..0..1..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 25 2016
STATUS
approved