Numbers k such that 3*R_k + 20 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A256463
Numbers k such that 3*R_k + 20 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =2a(2) =3a(3) =5a(4) =24a(5) =37a(6) =53a(7) =63a(8) =84a(9) =299a(10) =506a(11) =1687a(12) =6660a(13) =7473a(14) =8754a(15) =24048a(16) =68078a(17) =71223
External references
- oeis: A256463