A058211 Numbers k such that there is an arrangement of k points in the plane such that no point is on >= k/2 connecting lines.

9, 15, 19, 25, 31, 37

Offset

1,1

Comments

Counterexamples to a conjecture of Dirac.

References

H. T. Croft, K. J. Falconer and R. K. Guy, Unsolved Problems in Geometry, F12.

Links

Table of n, a(n) for n=1..6.

Crossrefs

Sequence in context: A070876 A266419 A161163 * A038599 A330438 A321342

Adjacent sequences: A058208 A058209 A058210 * A058212 A058213 A058214

Keyword

nonn,nice,hard,more

Author

N. J. A. Sloane, Nov 30 2000

Status

approved