OFFSET
1,1
COMMENTS
Column 2 of A203656.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 17*a(n-1) +28*a(n-2).
Conjectures from Colin Barker, Jun 04 2018: (Start)
G.f.: x*(81 + 140*x) / (1 - 17*x - 28*x^2).
a(n) = (2^(-1-n)*((17-sqrt(401))^n*(-77+5*sqrt(401)) + (17+sqrt(401))^n*(77+5*sqrt(401))))/sqrt(401).
(End)
EXAMPLE
Some solutions for n=4:
..3..1..2....3..4..3....2..2..1....0..3..2....2..0..1....4..4..4....1..2..4
..4..3..1....1..3..2....3..2..2....3..4..3....4..2..0....2..4..4....3..1..2
..2..4..3....2..1..3....1..3..2....3..3..3....1..4..2....1..2..4....0..3..1
..2..2..4....3..2..1....0..1..3....4..3..4....0..1..4....1..1..2....2..0..3
..1..2..2....2..4..2....4..0..1....4..4..1....1..3..1....0..1..1....0..4..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 04 2012
STATUS
approved