Numbers n such that 8*10^n + 5*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A103086

Numbers n such that 8*10^n + 5*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =1a(1) =2a(2) =8a(3) =17a(4) =19a(5) =25a(6) =40a(7) =49a(8) =58a(9) =59a(10) =92a(11) =113a(12) =296a(13) =637a(14) =1856a(15) =2515a(16) =3593a(17) =6991a(18) =11840a(19) =86072a(20) =93508

External references