OFFSET
1,1
COMMENTS
Row 3 of A223321.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 38*a(n-1) - 129*a(n-2) for n>4.
Empirical g.f.: x*(144 - 2347*x + 5451*x^2 - 40500*x^3) / (1 - 38*x + 129*x^2). - Colin Barker, Aug 19 2018
EXAMPLE
Some solutions for n=3:
..0..6..5....0..7..3....0..1..8....0..7.11....0..7.11....0..7..1....0..7..1
..4.10..4....3..8..2....0..1..8....3..7..3....0..7..1....1..2..8....1..8..4
.11..9..3....1..8..1....2..1..2....3..9..8...11..3..7....0..1..7....9..8..4
Vertex neighbors:
0 -> 1 2 5 6 7
1 -> 0 2 3 7 8
2 -> 0 1 4 6 8
3 -> 1 7 8 9 11
4 -> 2 6 8 9 10
5 -> 0 6 7 10 11
6 -> 0 2 4 5 10
7 -> 0 1 3 5 11
8 -> 1 2 3 4 9
9 -> 3 4 8 10 11
10 -> 4 5 6 9 11
11 -> 3 5 7 9 10
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 19 2013
STATUS
approved