OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) + 16*a(n-2) - 16*a(n-3) - 41*a(n-4) + 16*a(n-5) + 16*a(n-6) - 4*a(n-7) - a(n-8).
Empirical g.f.: x*(10 + 8*x - 47*x^2 - 28*x^3 + 31*x^4 + 12*x^5 - 5*x^6 - x^7) / ((1 + x - x^2)*(1 - x - x^2)*(1 - 4*x - 13*x^2 + 4*x^3 + x^4)). - Colin Barker, Jan 07 2019
EXAMPLE
Some solutions for n=4:
..3..4..2....5..1..2....0..4..5....3..1..2....0..1..2....3..4..5....3..1..2
..0..1..5....0..7..8....3..1..2....0..4..5....3..7..8....0..1..2....8..7..0
..9..7..8....6..4..3....9..7.11....6..7.11....6..4..5....6.10..8...11..4..5
.14.13..6...14.13.11....6.13..8...12.13..8....9.10.14...12..7.11...12.10..6
.12.10.11...12.10..9...12.10.14....9.10.14...12.13.11....9.13.14....9.13.14
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 10 2015
STATUS
approved