Or, very simply stated, given the finite set $S$ = {$a_1, ... , a_k$}$S = \{a_1, \dots , a_k\}$, consider the diophantine equation: $$(n-a_1)...(n-a_n)=0$$.$$(n-a_1)\dots(n-a_k)=0.$$ EDIT: Then we can write S as {$ \ n \ | \ \exists x : (n-a_1)...(n-a_k)=0$ }$\{ \ n \ | \ \exists x : (n-a_1)\dots(n-a_k)=0\ \}$. (Thanks David)