Numbers n such that 9*10^n + 6*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103103
Numbers n such that 9*10^n + 6*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =3a(1) =4a(2) =5a(3) =6a(4) =8a(5) =16a(6) =34a(7) =41a(8) =52a(9) =89a(10) =105a(11) =322a(12) =635a(13) =940a(14) =944a(15) =1131a(16) =1198a(17) =1743a(18) =1872a(19) =37914a(20) =41656a(21) =90096a(22) =99474a(23) =113468a(24) =140337a(25) =180432a(26) =263523
External references
- oeis: A103103