Numbers n such that 5*10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

A103017

Numbers n such that 5*10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =4a(4) =7a(5) =22a(6) =28a(7) =36a(8) =109a(9) =155a(10) =868a(11) =1777a(12) =2465a(13) =3874a(14) =4506a(15) =4684a(16) =5503a(17) =13975a(18) =15632a(19) =33054a(20) =34307a(21) =50495a(22) =60631a(23) =62328a(24) =92513a(25) =92869

External references