Numbers k such that 7*10^k + 8*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A103067
Numbers k such that 7*10^k + 8*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =4a(2) =18a(3) =28a(4) =55a(5) =1728a(6) =1876a(7) =1884a(8) =6841a(9) =10782a(10) =25366a(11) =98446a(12) =137250
External references
- oeis: A103067