Is there a set $A$ of positive integers such that - $\sum_{n \in A} \frac{1}{n} = \infty$, and - there is no polynomial $f \in \mathbb{Z}[x]$ of degree at least $2$ which takes infinitely many values in $A$? <b>Added on Feb 16, 2015:</b> Seva gave a complete answer to this question; though a little later, he claimed a <b>great deal</b> more -- his claim amounts to the following: > <b>Claim:</b> There is a partition of $\mathbb{N}$ into > > - a set $A$ of asymptotic density $1$ of *'non-values of non-linear polynomials'*, > which has finite intersection with the image of any polynomial $f \in \mathbb{Z}[x]$ > of degree $\geq 2$, and > > - a set $B$ of asymptotic density $0$ of *'values of non-linear polynomials'*, > which contains all but finitely many positive values taken by any polynomial > $f \in \mathbb{Z}[x]$ of degree $\geq 2$. If Seva is right, can the construction of such partition of $\mathbb{N}$ be made more explicit?