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%I #14 May 22 2021 04:32:56
%S 3,6,8,11,17,28,30,45
%N Maximum cardinality of isosceles sets in E^n.
%C An isosceles set is a set of points in a plane or in space, any three of which form an isosceles triangle.
%C In his 1946 problem Erdős notes that a(2) = 6 and asks for the value of a(3); L. M. Kelly proves that a(2) = 6 and shows that a(3) >= 9. The editors note that Kelly disproves a conjecture of Coxeter. - _Charles R Greathouse IV_, May 21 2021
%H Paul Erdős, <a href="https://www.jstor.org/stable/2305860">Problems for Solution: E735</a>, The American Mathematical Monthly, vol. 53, no. 7 (August 1946), p. 394.
%H Paul Erdős and L. M. Kelly, <a href="https://www.jstor.org/stable/2304710">Isosceles n-points</a>, The American Mathematical Monthly, vol. 54, no. 4 (April 1947), pp. 227-229.
%H Yury J. Ionin, <a href="https://doi.org/10.37236/230">Isosceles Sets</a>, The Electronic Journal of Combinatorics, Vol. 16, No. 1 (2009), R141.
%Y Cf. A027627.
%K nonn,more,hard
%O 1,1
%A _John W. Layman_, Sep 01 2010
%E Comment corrected by _John W. Layman_, Sep 03 2010