Numbers n such that 8*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103081
Numbers n such that 8*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =0a(1) =3a(2) =5a(3) =101a(4) =105a(5) =4097a(6) =5733a(7) =9755a(8) =31833
External references
- oeis: A103081