Primes of the form 7*10^k + R_k, where R_k is the repunit (A002275) of length k.

A093632

Primes of the form 7*10^k + R_k, where R_k is the repunit (A002275) of length k.

Terms

    a(0) =7a(1) =71a(2) =71111111

External references