a(n) = smallest prime >= the smallest positive integer with exactly n divisors.

Terms

a(0) =2a(1) =2a(2) =5a(3) =7a(4) =17a(5) =13a(6) =67a(7) =29a(8) =37a(9) =53a(10) =1031a(11) =61a(12) =4099a(13) =193a(14) =149a(15) =127a(16) =65537a(17) =181a(18) =262147a(19) =241a(20) =577a(21) =3079a(22) =4194319a(23) =367a(24) =1297a(25) =12289a(26) =907a(27) =967a(28) =268435459a(29) =727