Least prime factor of 2^n + 5^n.

Terms

a(0) =2a(1) =7a(2) =29a(3) =7a(4) =641a(5) =7a(6) =29a(7) =7a(8) =17a(9) =7a(10) =29a(11) =7a(12) =641a(13) =7a(14) =29a(15) =7a(16) =97a(17) =7a(18) =29a(19) =7a(20) =641a(21) =7a(22) =29a(23) =7a(24) =17a(25) =7a(26) =29a(27) =7a(28) =641a(29) =7