A construction for this unique graph comes from number theory. An integer a is a quadratic residue modulo n if an x exists such that a ≡ x2 (mod n). For a prime p such that p ≡ 3 (mod 4), we know that i is a quadratic residue if and only if p-i is not a quadratic residue. Given a prime p ≡ 3 (mod 4), the quadratic residues modulo p form a rotational p-tournament. {1, 4, 5, 6, 7, 9, 11, 16, 17} are the quadratic residues of 19. 1≡12(mod 19), 4≡22(mod 19), 5≡92(mod 19), 6≡52(mod 19), 7≡82(mod 19), 9≡32(mod 19), 11≡72(mod 19), 16≡ 42(mod 19), 17≡62(mod 19). The same thing is happening with the 3 player game above -- the quadratic residues of 7 are {1,2,4}.