Numbers k such that R_(k+2) + 10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A256925
Numbers k such that R_(k+2) + 10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =136a(1) =184a(2) =640a(3) =37960a(4) =217360
External references
- oeis: A256925