Numbers k such that 10^k + 7*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102943
Numbers k such that 10^k + 7*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =2a(2) =8a(3) =10a(4) =25a(5) =50a(6) =76a(7) =104a(8) =4406a(9) =8935a(10) =26000a(11) =31652
External references
- oeis: A102943