Smallest prime power >= n.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =7a(6) =7a(7) =8a(8) =9a(9) =11a(10) =11a(11) =13a(12) =13a(13) =16a(14) =16a(15) =16a(16) =17a(17) =19a(18) =19a(19) =23a(20) =23a(21) =23a(22) =23a(23) =25a(24) =25a(25) =27a(26) =27a(27) =29a(28) =29a(29) =31