Numbers k such that 5*10^k - 9 is prime.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =24a(5) =172a(6) =173a(7) =218a(8) =439a(9) =2563a(10) =2782a(11) =2880a(12) =3715a(13) =4392a(14) =10820a(15) =14592a(16) =25054a(17) =27769a(18) =40168a(19) =180992a(20) =193907