Numbers n such that 8*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A103091

Numbers n such that 8*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =1a(1) =3a(2) =6a(3) =31a(4) =36a(5) =61a(6) =117a(7) =229a(8) =339a(9) =3165a(10) =3958a(11) =5277a(12) =5343a(13) =6079a(14) =6535a(15) =8485a(16) =15084a(17) =34537

External references