Numbers n such that 9*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103099
Numbers n such that 9*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =1a(1) =2a(2) =4a(3) =25a(4) =58a(5) =148a(6) =373a(7) =421a(8) =1915a(9) =3746a(10) =16784a(11) =30050a(12) =60026a(13) =93346
External references
- oeis: A103099