Even-indexed primes: a(n) = prime(2n).

Terms

a(0) =3a(1) =7a(2) =13a(3) =19a(4) =29a(5) =37a(6) =43a(7) =53a(8) =61a(9) =71a(10) =79a(11) =89a(12) =101a(13) =107a(14) =113a(15) =131a(16) =139a(17) =151a(18) =163a(19) =173a(20) =181a(21) =193a(22) =199a(23) =223a(24) =229a(25) =239a(26) =251a(27) =263a(28) =271a(29) =281