OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-2) + 4*a(n-3) - a(n-4) - a(n-6).
Empirical g.f.: x*(2 + 4*x + 3*x^2 - x^3 - x^4 - x^5) / (1 - 2*x - x^2 - 4*x^3 + x^4 + x^6). - Colin Barker, Jan 06 2019
EXAMPLE
Some solutions for n=4:
..1..5..2..7..4....0..1..6..3..4....1..2..6..7..4....2..5..6..4..8
..6..0..8..9..3....5..7..8..2..9....5..0..8..9..3....7..0..1..9..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 09 2015
STATUS
approved