Numbers n such that 8*10^n + 7*R_n - 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103089
Numbers n such that 8*10^n + 7*R_n - 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =0a(1) =5a(2) =6a(3) =185a(4) =401a(5) =480a(6) =1319a(7) =5646a(8) =6029a(9) =16824a(10) =62387a(11) =70638
External references
- oeis: A103089