Numbers k such that 10*R_k + 3 is prime, where R_k is the repunit (A002275) of length k.
A056654
Numbers k such that 10*R_k + 3 is prime, where R_k is the repunit (A002275) of length k.
Terms
- a(0) =0a(1) =1a(2) =2a(3) =4a(4) =8a(5) =10a(6) =23a(7) =83a(8) =220a(9) =1313a(10) =2951a(11) =20015a(12) =51053
External references
- oeis: A056654