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A058211 Numbers n such that there is an arrangement of n points in the plane such that no point is on >= n/2 connecting lines. 0
9, 15, 19, 25, 31, 37 (list; graph; refs; listen; history; text; internal format)
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 A321342 A255763

Adjacent sequences:  A058208 A058209 A058210 * A058212 A058213 A058214

KEYWORD

nonn,nice,hard

AUTHOR

N. J. A. Sloane, Nov 30 2000

STATUS

approved

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Last modified March 26 00:16 EDT 2019. Contains 321477 sequences. (Running on oeis4.)