OFFSET
0,3
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..50
EXAMPLE
Some solutions for n=3:
..x..0..x..1....x..0..x..1....x..0..x..1....x..0..x..1....x..0..x..1
..2..x..3..x....2..x..3..x....2..x..3..x....1..x..2..x....2..x..3..x
..x..1..x..4....x..4..x..5....x..1..x..2....x..3..x..0....x..1..x..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 22 2012
EXTENSIONS
a(0)=1 prepended and terms a(15) and beyond from Andrew Howroyd, Jun 25 2017
STATUS
approved