Numbers k such that 7*10^k + 5*R_k - 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A103061
Numbers k such that 7*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) =4a(3) =18a(4) =19a(5) =646a(6) =814a(7) =5794a(8) =16524a(9) =19495a(10) =26010a(11) =29238a(12) =72120
External references
- oeis: A103061