a(1) = 7, a(n) = least k such that concatenation of n copies of k with all previous concatenation gives a prime.
A111475
a(1) = 7, a(n) = least k such that concatenation of n copies of k with all previous concatenation gives a prime.
Terms
- a(0) =7a(1) =3a(2) =1a(3) =1a(4) =1a(5) =1a(6) =129a(7) =123a(8) =97a(9) =559a(10) =781a(11) =459a(12) =253a(13) =183a(14) =413a(15) =417a(16) =657a(17) =77a(18) =437a(19) =1439a(20) =667a(21) =1281a(22) =3379a(23) =979a(24) =2763a(25) =1953a(26) =103a(27) =10083a(28) =5103a(29) =291
External references
- oeis: A111475