OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-2) + 2*a(n-3) + a(n-4) - a(n-5).
Empirical g.f.: x*(3 + x + x^2 - x^3) / (1 - 3*x^2 - 2*x^3 - x^4 + x^5). - Colin Barker, Jan 08 2019
EXAMPLE
Some solutions for n=4:
.12..6..7..4..9....5..6.14..8..9...12..6..7..8..9....5..6.14..8..9
.10.11..2.13.14...10.11.12.13..4...10.11..2.13..4...10..7.12.13..4
..5..0..1..8..3....1..0..7..2..3....5..0..1.14..3...11..0..1..2..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 14 2015
STATUS
approved