Numbers n such that 9*10^n + 8*R_n - 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
A103107
Numbers n such that 9*10^n + 8*R_n - 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
Terms
- a(0) =0a(1) =6a(2) =9a(3) =90a(4) =111a(5) =210a(6) =237a(7) =414a(8) =1192a(9) =1260a(10) =5836a(11) =6772a(12) =24861a(13) =52431
External references
- oeis: A103107