Numbers n such that 3*10^n + 2*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A102966

Numbers n such that 3*10^n + 2*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =0a(1) =1a(2) =3a(3) =6a(4) =12a(5) =408a(6) =649a(7) =949a(8) =963a(9) =1005a(10) =2700a(11) =19779a(12) =22518a(13) =22611a(14) =40584a(15) =55362a(16) =70194

External references