Problem 9

Erdős Problem #9: declared status 'open'. Formalized: yes. Let $A$ be the set of all odd integers not of the form $p+2^{k}+2^l$ (where $k,l\geq 0$ and $p$ is prime). Is the upper density of $A$ positive? Prize: no. OEIS: A006286. Tags: additive basis, number theory, primes.