Numbers k such that 4*R_k + 7*10^k + 3 is prime, where R_k = 11...11 is the repunit (A002275) of length k.
A259136
Numbers k such that 4*R_k + 7*10^k + 3 is prime, where R_k = 11...11 is the repunit (A002275) of length k.
Terms
- a(0) =10a(1) =30a(2) =120a(3) =484a(4) =1486a(5) =1578a(6) =13672a(7) =13810a(8) =15094a(9) =72772a(10) =94212
External references
- oeis: A259136