Numbers k such that 8*10^k + R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
A056722
Numbers k such that 8*10^k + R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.
Terms
- a(0) =2a(1) =3a(2) =26a(3) =110a(4) =141a(5) =474a(6) =902a(7) =1746a(8) =2997a(9) =3627a(10) =3788a(11) =51162a(12) =71670a(13) =78576a(14) =104942a(15) =122592a(16) =248145
External references
- oeis: A056722