OFFSET
1,1
COMMENTS
Column 1 of A223218.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + 4*a(n-2) = 6*A063782(n-1).
Conjectures from Colin Barker, Aug 17 2018: (Start)
G.f.: 6*x*(1 + x) / (1 - 2*x - 4*x^2).
a(n) = (3*((1-sqrt(5))^n*(-3+sqrt(5)) + (1+sqrt(5))^n*(3+sqrt(5)))) / (4*sqrt(5)).
(End)
EXAMPLE
Some solutions for n=3:
..4....4....0....2....1....4....2....3....2....2....0....5....1....3....4....5
..2....1....1....5....2....2....1....1....0....1....1....4....3....4....3....2
..0....4....4....2....0....4....2....0....2....0....0....2....1....1....1....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 18 2013
STATUS
approved