Numbers n such that 8*10^n + 4*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A103079

Numbers n such that 8*10^n + 4*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =0a(1) =26a(2) =36a(3) =38a(4) =60a(5) =80a(6) =92a(7) =174a(8) =486a(9) =627a(10) =999a(11) =1614a(12) =4382a(13) =4898a(14) =8442a(15) =17262a(16) =17802a(17) =35427a(18) =40743

External references