Numbers k such that 10^k + 6*R_k - 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102939
Numbers k such that 10^k + 6*R_k - 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =2a(2) =3a(3) =18a(4) =177a(5) =324a(6) =388a(7) =392a(8) =404a(9) =531a(10) =1083a(11) =12546a(12) =22443a(13) =54388a(14) =72916a(15) =185520
External references
- oeis: A102939