Aurifeuillian primes of the form 2^k+1.

Terms

a(0) =3a(1) =5a(2) =11a(3) =13a(4) =17a(5) =43a(6) =241a(7) =257a(8) =331a(9) =683a(10) =2731a(11) =5419a(12) =43691a(13) =61681a(14) =65537a(15) =174763a(16) =2796203a(17) =15790321a(18) =18837001a(19) =22366891a(20) =715827883a(21) =4278255361a(22) =4562284561a(23) =77158673929