Numbers k such that 3*10^k + 6*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A102975
Numbers k such that 3*10^k + 6*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =2a(2) =12a(3) =15a(4) =51a(5) =194a(6) =498a(7) =2136a(8) =2822a(9) =3762a(10) =7428a(11) =22740a(12) =30452a(13) =37952a(14) =55254
External references
- oeis: A102975