Numbers n for which 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A096846
Numbers n for which 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =1a(1) =3a(2) =4a(3) =6a(4) =9a(5) =12a(6) =72a(7) =118a(8) =124a(9) =190a(10) =244a(11) =304a(12) =357a(13) =1422a(14) =2691a(15) =5538a(16) =7581a(17) =21906a(18) =32176a(19) =44358a(20) =120552a(21) =137073a(22) =152260
External references
- oeis: A096846