OFFSET
0,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..50
EXAMPLE
Some solutions for n=3:
..x..0..x..1..x..2..x....x..0..x..1..x..2..x....x..0..x..1..x..2..x
..1..x..3..x..0..x..4....3..x..4..x..5..x..1....3..x..4..x..3..x..5
..x..5..x..4..x..6..x....x..6..x..7..x..0..x....x..5..x..6..x..1..x
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 22 2012
EXTENSIONS
a(0)=1 prepended and terms a(7) and beyond from Andrew Howroyd, Jun 26 2017
STATUS
approved