PRIME LEHMER AND LUCAS NUMBERS WITH COMPOSITE INDICES

Let R(L, M) and U(P, Q) denote the Lehmer and Lucas sequences, respectively. It is shown that if R(L, M) and U(P, Q) are nondegenerate, then R-n (L, M) and U-n (P, Q) can be prime for composite n only if n epsilon {4, 6, 8, 9, 10, 14, 15, 21, 25, 26, 49, 65}. Moreover, all instances in which R-n (L, M) or U-m (P, Q) are prime are explicitly given when n E {14,15,21,26,49,65} and m epsilon {6,8,10,15,25,26,65}.