Numbers k such that 3*10^k + 5*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102972
Numbers k such that 3*10^k + 5*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =1a(2) =3a(3) =6a(4) =12a(5) =33a(6) =69a(7) =111a(8) =1965a(9) =5646a(10) =7404a(11) =11103a(12) =20790a(13) =24840a(14) =38199a(15) =90669
External references
- oeis: A102972