Numbers n such that 2*10^n + 4*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A102955
Numbers n such that 2*10^n + 4*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =1a(1) =15a(2) =31a(3) =73a(4) =97a(5) =499a(6) =4207a(7) =5902a(8) =9568a(9) =12142a(10) =13048a(11) =38341a(12) =80167a(13) =91903
External references
- oeis: A102955