Numbers n such that 9*10^n + 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103108
Numbers n such that 9*10^n + 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =2a(1) =3a(2) =32a(3) =42a(4) =75a(5) =368a(6) =1392a(7) =16350a(8) =49101a(9) =49689a(10) =91839
External references
- oeis: A103108