Numbers n such that 6*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103040
Numbers n such that 6*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =1a(1) =4a(2) =9a(3) =21a(4) =48a(5) =84a(6) =696a(7) =1489a(8) =4167a(9) =8400a(10) =52099
External references
- oeis: A103040