Prime following n-th repunit.

Terms

a(0) =2a(1) =13a(2) =113a(3) =1117a(4) =11113a(5) =111119a(6) =1111151a(7) =11111117a(8) =111111113a(9) =1111111121a(10) =11111111113a(11) =111111111149