a(n) = nextprime(n) + n.

Terms

a(0) =2a(1) =3a(2) =5a(3) =8a(4) =9a(5) =12a(6) =13a(7) =18a(8) =19a(9) =20a(10) =21a(11) =24a(12) =25a(13) =30a(14) =31a(15) =32a(16) =33a(17) =36a(18) =37a(19) =42a(20) =43a(21) =44a(22) =45a(23) =52a(24) =53a(25) =54a(26) =55a(27) =56a(28) =57a(29) =60