Numbers k such that 9*R_k + 7*10^k - 2 is prime, where R_k = 11...11 is the repunit (A002275) of length k.
A259134
Numbers k such that 9*R_k + 7*10^k - 2 is prime, where R_k = 11...11 is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =2a(2) =4a(3) =28a(4) =156a(5) =322a(6) =352a(7) =1212a(8) =1284a(9) =7984a(10) =15192a(11) =84772a(12) =119930a(13) =148860
External references
- oeis: A259134