Numbers k such that 8*R_k + 10^k - 7 is prime, where R_k = 11...11 is the repunit (A002275) of length k.
A259119
Numbers k such that 8*R_k + 10^k - 7 is prime, where R_k = 11...11 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =2a(2) =8a(3) =14a(4) =40a(5) =92a(6) =128a(7) =884a(8) =9424a(9) =14768a(10) =19258a(11) =31234
External references
- oeis: A259119