Integers such that Difference with Power of 2 is always Prime/Examples

Examples of Integers such that Difference with Power of 2 is always Prime
The following positive integers are believed to be the only values of $n$ such that:
 * $\forall k > 0: n - 2^k$

is prime whenever it is (strictly) positive:


 * $4, 7, 15, 21, 45, 75, 105$