Numbers k such that 7*R_k - 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A099419
Numbers k such that 7*R_k - 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =2a(1) =13a(2) =20a(3) =23a(4) =31a(5) =100a(6) =241a(7) =275a(8) =925a(9) =1067a(10) =1369a(11) =2065a(12) =7163a(13) =37963a(14) =91856a(15) =111706a(16) =260198a(17) =271757a(18) =314564a(19) =348724
External references
- oeis: A099419