King Albrecht founded a family. In the family everyone has exactly $ 8$ children. The only, but really important rule is that among the grandchildren of any person at most $x$ can be named Bela. (None of Albrecht’s children is called Bela.) For which $x$ is it possible that after a certain time each newborn in the family has at least one direct ancestor in the Royal family called Bela. No two of Albrecht’s descendants (including himself) have a common child.
Problem
Source: 2021 Dürer Math Competition Finals Day2 E15 https://artofproblemsolving.com/community/c2749870_
Tags: combinatorics