OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..105
FORMULA
Empirical: a(n) = 33*a(n-1) - 207*a(n-2) + 175*a(n-3).
Conjectures from Colin Barker, Jan 03 2019: (Start)
G.f.: 16*x / ((1 - x)*(1 - 7*x)*(1 - 25*x)).
a(n) = (3 - 4*7^(1+n) + 25^(1+n)) / 27.
(End)
EXAMPLE
Some solutions for n=2:
..1..1..0..1....0..1..1..1....1..0..1..0....1..1..0..1....0..0..0..1
..0..1..1..1....1..1..0..1....1..0..1..0....0..1..0..0....0..1..1..1
..1..0..1..0....1..0..1..0....0..1..0..0....1..1..0..1....0..1..0..0
..1..1..0..1....0..0..0..1....1..0..1..0....0..1..1..1....1..0..1..0
..1..1..0..1....0..0..0..1....0..1..0..0....0..0..0..1....1..0..1..0
..0..1..1..1....1..1..0..1....0..0..0..1....0..1..0..0....1..1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 29 2015
STATUS
approved