Problem

Source: 2012 Indonesia Round 2.5 TST 2 Problem 2

Tags: combinatorics proposed, combinatorics



The positive integers are colored with black and white such that: - There exists a bijection from the black numbers to the white numbers, - The sum of three black numbers is a black number, and - The sum of three white numbers is a white number. Find the number of possible colorings that satisfies the above conditions.