Numbers k such that 7*10^k + R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A103050
Numbers k such that 7*10^k + R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =7a(2) =133a(3) =938a(4) =17666a(5) =20864a(6) =56756
External references
- oeis: A103050