Numbers n such that 6*10^n + 4*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103034
Numbers n such that 6*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) =1a(2) =2a(3) =7a(4) =19a(5) =25a(6) =37a(7) =49a(8) =133a(9) =613a(10) =1340a(11) =2036a(12) =2491a(13) =26263
External references
- oeis: A103034