Numbers n such that 9*10^n + 2*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A103093

Numbers n such that 9*10^n + 2*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =3a(1) =4a(2) =24a(3) =39a(4) =63a(5) =76a(6) =108a(7) =166a(8) =520a(9) =1810a(10) =2349a(11) =2562a(12) =5784a(13) =6448a(14) =11692a(15) =16036a(16) =17554

External references