MathDB
Combinatorics

Source: Baltic Way 2015

November 8, 2015
combinatoricscombinatorial geometry

Problem Statement

For n2n\geq 2 , an equilateral triangle is divided into n2n^2 congruent smaller equilateral triangles. Detemine all ways in which real numbers can be assigned to the (n+1)(n+2)2\frac{(n+1)(n+2)}{2} vertices so that three such numbers sum to zero whenever the three vertices form a triangle with edges parallel to the sides of the big triangle.