Other terms are a(25)=1558 and a(43)=5718. All values in the sequence are Fermat and Lucas PRPs except for the first two which were proved with ECM. The larger values won't be easily provable until RSA-640 is factored, which has a prize of $20,000 for its factorization. This sequence is based on a suggestion of Jens Kruse Andersen.

RSA-640 was factored in 2005; see the Wikipedia link. - D. S. McNeil, Nov 26 2010