Numbers n such that 9*10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103095
Numbers n such that 9*10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =1a(1) =3a(2) =4a(3) =15a(4) =153a(5) =322a(6) =471a(7) =561a(8) =664a(9) =2157a(10) =3697a(11) =14875a(12) =19270a(13) =22095
External references
- oeis: A103095