Let U(P, Q) and V(P, Q) be Lucas sequences generated by P and Q, and define D congruent P^2 - 4Q. Let n be an odd composite number with (n, D) = 1, and n - (D/n) = 2^s d with d odd and s>=0, where (a/b) is the Legendre symbol. If U_d congruent 0 (mod n) or V_(2^r d) congruent 0 (mod n) for some r with 0<=r

extra strong Lucas pseudoprime | Lucas pseudoprime