This conjecture
The set of numbers of the form $q_1+q_2^2+q_3^3+q_4^4+q_5^5$ where all $q_k$ are primes.
would be true if for every odd $n>351$ , there are primes $a,b,c$ with $a^3+b^2+c=n$.
Is this conjecture true , or is there at least a heuristic for it ?