Numbers k such that 5*R_k + 3*10^k - 2 is prime, where R_k = 11...11 is the repunit (A002275) of length k.
A259126
Numbers k such that 5*R_k + 3*10^k - 2 is prime, where R_k = 11...11 is the repunit (A002275) of length k.
Terms
- a(0) =2a(1) =8a(2) =140a(3) =230a(4) =426a(5) =462a(6) =726a(7) =1974a(8) =7230a(9) =45860a(10) =47304
External references
- oeis: A259126