Numbers k such that 10^k + 8*R_k - 5 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102944
Numbers k such that 10^k + 8*R_k - 5 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =16a(2) =22a(3) =28a(4) =34a(5) =90a(6) =2068a(7) =2374a(8) =2854a(9) =3720a(10) =4242a(11) =22666a(12) =29292a(13) =29508
External references
- oeis: A102944