Numbers k such that (14*10^k - 131)/9 is prime.

Terms

a(0) =4a(1) =7a(2) =10a(3) =27a(4) =40a(5) =43a(6) =55a(7) =61a(8) =63a(9) =117a(10) =259a(11) =417a(12) =427a(13) =561a(14) =568a(15) =889a(16) =1335a(17) =26625a(18) =36613a(19) =45261a(20) =47205