Numbers k such that 80*R_k + 7 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A056695
Numbers k such that 80*R_k + 7 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =2a(2) =3a(3) =5a(4) =8a(5) =11a(6) =71a(7) =117a(8) =123a(9) =189a(10) =243a(11) =303a(12) =356a(13) =1421a(14) =2690a(15) =5537a(16) =7580a(17) =21905a(18) =32175a(19) =44357
External references
- oeis: A056695