Numbers k such that 3*10^k + 8*R_k - 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102979
Numbers k such that 3*10^k + 8*R_k - 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =1a(2) =6a(3) =10176a(4) =56898
External references
- oeis: A102979