Since q/(k + 1) < 1, we have k ≤ p. Since k < p contradicts (2), we have k = p, but this implies q = r = 0 and hence k = N by (1). Contradiction. Therefore k < N if k ∈K(N). Suppose k ∈K(N). Then (3) implies N −1 | k(k−1)(k + 1). Because N 6≡ 1 (mod 4),there exist pairwise relatively prime integers d, d1, and d2 such that