Primes of the form 10*R_k + 7, where R_k is the repunit (A002275) of length k.
A093139
Primes of the form 10*R_k + 7, where R_k is the repunit (A002275) of length k.
Terms
- a(0) =7a(1) =17a(2) =1117a(3) =11117a(4) =11111117
External references
- oeis: A093139