[math-fun] Asymptotic question

I recently read that every sufficiently large integer in Z+ is representable as a linear combination — with coefficients in N_0 := {0,1,2,...} — of the first n primes P_n := {p_1,...,p_n} . (Actually this holds for relatively prime integers.) Let f(n) denote the largest integer *not* expressible as an N_0 combination of the primes in P_n with all coefficients nonnegative. I've also read there is no known expression for f(n). So: Is there a simple asymptotic expression for f(n) as n -> oo ??? ——Dan