Numbers n such that repunit(n) concatenated with its 10's complement is prime; or numbers n such that (1+7*10^n+100^n)/9 is prime.
A108966
Numbers n such that repunit(n) concatenated with its 10's complement is prime; or numbers n such that (1+7*10^n+100^n)/9 is prime.
Terms
- a(0) =1a(1) =5a(2) =16a(3) =36a(4) =61a(5) =149a(6) =725a(7) =1104a(8) =1276a(9) =1289a(10) =8575
External references
- oeis: A108966