Numbers k such that 5*10^k + R_k + 2 is a prime, where R_k = 11...1 is the repunit (A002275) of length k.
A103005
Numbers k such that 5*10^k + R_k + 2 is a prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =1a(1) =3a(2) =19a(3) =109a(4) =129a(5) =280a(6) =387a(7) =447a(8) =487a(9) =1048a(10) =3298a(11) =3460a(12) =9454a(13) =26103a(14) =61693a(15) =66469
External references
- oeis: A103005