Numbers k such that 10^k + 3*R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A056698
Numbers k such that 10^k + 3*R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =15a(2) =41a(3) =83a(4) =95a(5) =341a(6) =551a(7) =669a(8) =989a(9) =1223a(10) =6923a(11) =103703
External references
- oeis: A056698