Numbers k such that 2*10^k + 5*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

A099006

Numbers k such that 2*10^k + 5*R_k + 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

Terms

    a(0) =2a(1) =3a(2) =26a(3) =27a(4) =45a(5) =62a(6) =147a(7) =1277a(8) =1665a(9) =1979a(10) =2970a(11) =12773a(12) =17702a(13) =19128a(14) =22206a(15) =22386a(16) =25053

External references