Primes of the form 40*R_k + 1, where R_k is the repunit (A002275) of length k.

A093174

Primes of the form 40*R_k + 1, where R_k is the repunit (A002275) of length k.

Terms

    a(0) =41a(1) =4441a(2) =44444444441

External references