OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..105
FORMULA
Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 13*a(n-3) - 11*a(n-4) + 6*a(n-5) - a(n-6).
Empirical g.f.: x*(1 - 3*x + 5*x^2 - 6*x^3 + 5*x^4 - x^5) / (1 - 6*x + 11*x^2 - 13*x^3 + 11*x^4 - 6*x^5 + x^6). - Colin Barker, Jan 08 2019
EXAMPLE
Some solutions for n=3:
..5..4..0....3..4..0....3..4..5....3..4..0....5..4..0....3..4..5....3..4..0
..8..1..2....8..1..2....0..1..2....6..1..2....8..1..2....0..1..2....8..1..2
..3.10..6...11.10..5....9.10.11....9.10..5....3.10.11....9.10..6....9.10..5
.14..7..9....6..7.14....6..7..8...14..7..8....6..7.14...14..7..8....6..7.14
.17.16.11....9.16.17...15.16.17...17.16.11....9.16.17...17.16.11...17.16.11
.12.13.15...12.13.15...12.13.14...12.13.15...12.13.15...12.13.15...12.13.15
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 16 2015
STATUS
approved