Smallest prime starting with n 5s.

Terms

a(0) =2a(1) =5a(2) =557a(3) =5557a(4) =555521a(5) =555557a(6) =55555517a(7) =55555553a(8) =5555555501a(9) =5555555557a(10) =555555555551a(11) =555555555551