Numbers n such that 9*10^n + 5*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103101
Numbers n such that 9*10^n + 5*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =0a(1) =2a(2) =20a(3) =104a(4) =329a(5) =1442a(6) =1721a(7) =24887
External references
- oeis: A103101