MathDB
2020 BAMO-12: 5

Source:

February 28, 2020

Problem Statement

Let SS be a set of a+b+3a+b+3 points on a sphere, where aa, bb are nonnegative integers and no four points of SS are coplanar. Determine how many planes pass through three points of SS and separate the remaining points into aa points on one side of the plane and bb points on the other side.