Numbers n such that 8*10^n + 2*R_n + 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103077
Numbers n such that 8*10^n + 2*R_n + 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =1a(1) =2a(2) =5a(3) =8a(4) =14a(5) =55a(6) =103a(7) =331a(8) =1067a(9) =13711a(10) =24397a(11) =54583
External references
- oeis: A103077