Numbers k such that 70*R_k + 9 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A056693
Numbers k such that 70*R_k + 9 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =65a(2) =85a(3) =89a(4) =101a(5) =385a(6) =623a(7) =7783a(8) =18535a(9) =113756a(10) =135878
External references
- oeis: A056693