Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #11 Dec 05 2018 04:54:26
%S 1,5,5,2,17,13,5,13,29,3,37,25,13,10,17,25,15,53,65,4,65,41,29,25,17,
%T 13,41,73,65,85,5,101,61,41,26,37,85,97,65,109,61,89,325,17,125,29,53,
%U 65,6,145,85,61,37,137,25,51,13,85,205,73,173,533,20,34,89,7,197,169,113,85
%N Numerators of rational-valued radii of circles given by 3 distinct integer points in the euclidean plane.
%C A triangle in the Euclidean plane defines a circumcircle. There exist only certain rational-valued circumradii if the vertices of the triangle have integer coordinates. They are rendered by the pair of sequences A128006/A128007 in increasing order.
%Y See A128007 for denominators.
%Y Cf. A128008, A128009, A128010, A128011, A192493, A192494.
%K frac,nonn
%O 1,2
%A _Heinrich Ludwig_, Feb 11 2007