Numbers whose number of divisors is prime (i.e., numbers of the form p^(q-1) for primes p,q).

Terms

a(0) =2a(1) =3a(2) =4a(3) =5a(4) =7a(5) =9a(6) =11a(7) =13a(8) =16a(9) =17a(10) =19a(11) =23a(12) =25a(13) =29a(14) =31a(15) =37a(16) =41a(17) =43a(18) =47a(19) =49a(20) =53a(21) =59a(22) =61a(23) =64a(24) =67a(25) =71a(26) =73a(27) =79a(28) =81a(29) =83