a(n) is the smallest k such that the sum of the first k primes is >= 10^n.

Terms

a(0) =1a(1) =3a(2) =9a(3) =25a(4) =68a(5) =191a(6) =547a(7) =1593a(8) =4692a(9) =13941a(10) =41710a(11) =125494a(12) =379324a(13) =1150976a(14) =3503793a(15) =10695889a(16) =32729282a(17) =100361004a(18) =308313172a(19) =948694980a(20) =2923428287a(21) =9020381557a(22) =27865631947a(23) =86174159206a(24) =266752375679a(25) =826469488966