(7^n)-th prime.

Terms

a(0) =2a(1) =17a(2) =227a(3) =2309a(4) =21391a(5) =185707a(6) =1549817a(7) =12579617a(8) =100061641a(9) =783765347a(10) =6065997263a(11) =46498768471a(12) =353628459043