Sum(prime(k)*10^(k),k=1..n).

Terms

a(0) =0a(1) =20a(2) =320a(3) =5320a(4) =75320a(5) =1175320a(6) =14175320a(7) =184175320a(8) =2084175320a(9) =25084175320a(10) =315084175320