Numbers n such that 8*10^n + 4*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103082
Numbers n such that 8*10^n + 4*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =0a(1) =1a(2) =4a(3) =13a(4) =37a(5) =46a(6) =106a(7) =139a(8) =469a(9) =5695a(10) =56281a(11) =58669
External references
- oeis: A103082