OFFSET
1,1
COMMENTS
Column 2 of A264059.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-2) + 3*a(n-3) - 9*a(n-4) + 3*a(n-5) - a(n-6) + 3*a(n-7) - a(n-8).
Empirical g.f.: x*(2 + 2*x - 4*x^2 - 7*x^3 + 2*x^4 + 2*x^5 + 2*x^6 - x^7) / ((1 - 3*x + x^2)*(1 - 3*x^3 + x^6)). - Colin Barker, Mar 20 2018
EXAMPLE
Some solutions for n=4:
..5..1..6....5..1..6....0..1..6....0..1..6....5..1..2....0..1..2....5..1..6
..3..4..0....3..4..0....8..4..5....3..4..5....8..4..0....8..4..9....3..4..0
..2..7..8....2..7.12....2..7..3....2..7.12...11..7..3...11..7..3....2..7.12
.14.10.11...14.10.11....9.10.11....9.10.11....9.10..6....5.10..6....9.10.11
.12.13..9....8.13..9...12.13.14....8.13.14...12.13.14...12.13.14....8.13.14
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 02 2015
STATUS
approved