Numbers k such that 10^k + 5*R_k - 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102936
Numbers k such that 10^k + 5*R_k - 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =3a(2) =6a(3) =15a(4) =70a(5) =76a(6) =13024a(7) =60346
External references
- oeis: A102936