Numbers k such that 3*10^k - 31 is prime.

Terms

a(0) =2a(1) =3a(2) =5a(3) =10a(4) =21a(5) =101a(6) =133a(7) =187a(8) =209a(9) =363a(10) =747a(11) =1550a(12) =3715a(13) =3875a(14) =6022a(15) =9729a(16) =10460a(17) =12316a(18) =14421a(19) =19023a(20) =50727