Does there exist a real number $c > 1$ such that for every natural number $n > 0$, the number $\lfloor c^n \rfloor$ is prime? I doubt such a number $c$ is known to exist, since the best similar results I've seen are much weaker. For example, in 1947 William Harold Mills proved that there is a real number $c > 1$ such that for every natural number $n > 0$, the number $\lfloor c^{3^n} \rfloor$ is prime: * Wikipedia, [Mills' constant](https://en.wikipedia.org/wiki/Mills%27_constant) and if the Riemann Hypothesis holds, the smallest such $c$ is approximately $$ c = 1.3063778838630806904686144926\ldots $$ Harder results along these lines are known, e.g. in 2010 Matomäki showed that there exists an uncountable infinity of real numbers $c > 1$ with the property that for every natural $n > 0$, the number $\lfloor c^{2^n} \rfloor$ is prime: * K. Matomäki, [Prime-representing functions](http://users.utu.fi/ksmato/papers/Primerepfunc.pdf), *Acta Mathematica Hungarica* **128** (4) (2010), 307–314. However, I haven't seen results like this for $\lfloor c^n \rfloor$. So, I think my question boils down to: is the answer to my original question known to be *no*, or is it still open?