a(n) is the (2^n)-th prime-indexed prime.

Terms

a(0) =3a(1) =5a(2) =17a(3) =67a(4) =241a(5) =739a(6) =2063a(7) =5441a(8) =13693a(9) =34351a(10) =83617a(11) =198479a(12) =465337a(13) =1076401a(14) =2461873a(15) =5582917a(16) =12548171a(17) =28018649a(18) =62133769a(19) =137034913a(20) =300736621a(21) =656953343a(22) =1429360349a(23) =3098240417a(24) =6692967079a(25) =14414137427a(26) =30952936639a(27) =66293412113a(28) =141636592337a(29) =301924957273