Numbers n such that 9*10^n + 6*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A103104

Numbers n such that 9*10^n + 6*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =1a(1) =2a(2) =4a(3) =7a(4) =13a(5) =28a(6) =58a(7) =86a(8) =92a(9) =108a(10) =1408a(11) =1486a(12) =1712a(13) =2674a(14) =3880a(15) =5536a(16) =7588a(17) =7650a(18) =10558a(19) =15532a(20) =17959a(21) =37180a(22) =93082

External references