Smallest k such that n times concatenation of k with itself followed by a 7 is a prime, or 0 if no such number exists.
A087605
Smallest k such that n times concatenation of k with itself followed by a 7 is a prime, or 0 if no such number exists.
Terms
- a(0) =1a(1) =2a(2) =1a(3) =1a(4) =3a(5) =100005a(6) =1a(7) =2a(8) =4a(9) =6a(10) =8a(11) =100010a(12) =19a(13) =2a(14) =215a(15) =9a(16) =60a(17) =100041a(18) =4a(19) =66a(20) =5a(21) =1a(22) =41a(23) =100061a(24) =4a(25) =15a(26) =2a(27) =1a(28) =195a(29) =100055
External references
- oeis: A087605