Numbers k such that 10^k + 8*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102945
Numbers k such that 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) =3a(2) =12a(3) =267a(4) =843a(5) =6300a(6) =37992a(7) =54117a(8) =121242a(9) =121621
External references
- oeis: A102945