1,2

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.

Table of n, a(n) for n=1..70.

See A128007 for denominators.

Cf. A128008, A128009, A128010, A128011, A192493, A192494.

Sequence in context: A023580 A021648 A287746 * A157703 A332507 A242617

Adjacent sequences: A128003 A128004 A128005 * A128007 A128008 A128009

frac,nonn

Heinrich Ludwig, Feb 11 2007

approved