Erdős problem 9
Is the upper density of the set of odd numbers that cannot be expressed as a prime plus two powers of 2 positive?
Sources
FormalConjectures/ErdosProblems/
9.lean
Retained formal statement
The set is known to be infinite. In [Er77c] Erdős credits Schinzel with proving that there are infinitely many odd integers not of this form, but gives no reference.
[Er77c] Erdős, P., _Problems and results on combinatorial number theory. III._.
Erdos9.Erdos9A.InfiniteSolvedStatement only, no proof