Numbers k such that 7*R_k - 50 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A256726
Numbers k such that 7*R_k - 50 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =3a(1) =4a(2) =7a(3) =12a(4) =15a(5) =48a(6) =87a(7) =138a(8) =342a(9) =675a(10) =901a(11) =1323a(12) =1362a(13) =1485a(14) =1909a(15) =9498a(16) =10941a(17) =11563a(18) =16308a(19) =37495a(20) =43875a(21) =71166a(22) =82960
External references
- oeis: A256726