Numbers k such that (10^k - 79)/3 is prime.

Terms

a(0) =2a(1) =3a(2) =4a(3) =7a(4) =9a(5) =15a(6) =57a(7) =63a(8) =147a(9) =178a(10) =202a(11) =697a(12) =713a(13) =952a(14) =1861a(15) =7433a(16) =14311a(17) =16737a(18) =29369a(19) =72723a(20) =121543