Numbers k such that 3*R_(k+2) - 2*10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.

A256326

Numbers k such that 3*R_(k+2) - 2*10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.

Terms

    a(0) =0a(1) =1a(2) =3a(3) =4a(4) =6a(5) =70a(6) =73a(7) =109a(8) =237a(9) =264a(10) =337a(11) =496a(12) =1029a(13) =1077a(14) =1254a(15) =1288a(16) =2049a(17) =3606a(18) =5035a(19) =9163a(20) =35899

External references