OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 4*a(n-2) - 4*a(n-3) for n>7.
Conjectures from Colin Barker, Jan 09 2019: (Start)
G.f.: x*(2 + 4*x - 5*x^2 - 21*x^3 + 10*x^4 - x^5 + 8*x^6) / ((1 - x)*(1 - 2*x)*(1 + 2*x)).
a(n) = (64 - 23*(-2)^n + 27*2^n) / 64 for n>4.
(End)
EXAMPLE
All solutions for n=4:
..1..3..1..1..1..1....1..2..2..1..1..2....1..3..1..1..1..1....0..0..0..0..0..0
..1..1..2..2..3..1....1..1..1..1..4..1....1..1..3..2..2..1....0..0..0..0..0..0
..1..2..2..3..1..1....1..4..1..1..1..1....1..3..2..2..1..1....0..0..0..0..0..0
..1..1..1..1..3..1....2..1..1..2..2..1....1..1..1..1..3..1....0..0..0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 19 2015
STATUS
approved