Primes by index in A001945.

Terms

a(0) =4a(1) =6a(2) =8a(3) =9a(4) =10a(5) =11a(6) =15a(7) =17a(8) =19a(9) =23a(10) =25a(11) =31a(12) =41a(13) =47a(14) =59a(15) =61a(16) =71a(17) =113a(18) =127a(19) =137a(20) =157a(21) =167a(22) =223a(23) =401a(24) =443a(25) =457a(26) =503a(27) =523a(28) =619a(29) =701