Numbers k such that (871*10^k - 7)/9 is prime.

Terms

a(0) =1a(1) =2a(2) =7a(3) =26a(4) =28a(5) =31a(6) =38a(7) =47a(8) =59a(9) =226a(10) =233a(11) =656a(12) =752a(13) =1073a(14) =1808a(15) =3646a(16) =4252a(17) =5246a(18) =24686a(19) =37952a(20) =59599