Numbers k such that 7*R_k - 10 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A256905
Numbers k such that 7*R_k - 10 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =2a(1) =11a(2) =24a(3) =42a(4) =56a(5) =336a(6) =738a(7) =2712a(8) =3498a(9) =8984a(10) =14036a(11) =46439
External references
- oeis: A256905