OFFSET
1,1
COMMENTS
Column 2 of A223255.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 5*a(n-1) - 2*a(n-2).
Conjectures from Colin Barker, Mar 16 2018: (Start)
G.f.: 4*x*(3 - 2*x) / (1 - 5*x + 2*x^2).
a(n) = (2^(1-n)*((5-sqrt(17))^n*(-1+sqrt(17)) + (1+sqrt(17))*(5+sqrt(17))^n)) / sqrt(17).
(End)
EXAMPLE
Some solutions for n=3:
..3..4....4..0....1..0....0..2....4..0....2..0....0..3....4..0....3..4....1..2
..4..0....0..2....0..4....3..0....0..2....0..2....2..0....0..4....4..0....0..1
..0..3....4..0....4..3....4..3....1..0....4..0....0..4....2..0....0..2....1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 18 2013
STATUS
approved