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Biribol Tournament Combinatorial Design

2175ExpertGraph TheoryCombinatorics

XXIII Olimpíada Iberoamericana de Matemática

In a biribol match, two teams of 4 people each compete. A biribol tournament is organized with $n$ participants, who form teams for each match (the teams are not fixed). At the end of the tournament, it was observed that every pair of people played exactly one match as opponents. For which values of $n$ is it possible to organize a tournament with such characteristics?
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