OFFSET
1,2
COMMENTS
Row 2 of A221087.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 7*a(n-1) - 7*a(n-3) + a(n-4).
Empirical g.f.: x^2*(2 - x)^2 / ((1 - x)*(1 + x)*(1 - 7*x + x^2)). - Colin Barker, Aug 03 2018
EXAMPLE
Some solutions for n=3:
..0..1..0....0..1..1....1..2..0....1..3..1....1..1..0....1..3..0....1..2..1
..2..3..0....0..3..1....1..2..0....0..1..0....0..3..1....0..1..1....0..2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 01 2013
STATUS
approved