On the other hand, if m > 26, then a ≥ (m − 2)/2 > 12 and the Primitive Divisor Theorem impliesintheexistenceofaprimitivedivisorpofFa whichinparticularsatisfiedp ≡ 1 (mod a). Thus mk ≥ p ≥ a−1 ≥ (m−4)/2 and the estimate (1) yields mk! ≥ ((m−4)/2e)(m−4)/2. Therefore, we use (8) to get