Numbers k such that 3*10^k + 7*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102977
Numbers k such that 3*10^k + 7*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =2a(2) =3a(3) =5a(4) =6a(5) =20a(6) =776a(7) =1185a(8) =3164a(9) =4212a(10) =10733a(11) =21726a(12) =38235
External references
- oeis: A102977