  Let $f(n)$ count the number of subsets of $\{1,...,n\}$ without an element
dividing another. In this paper I show that $f(n)$ grows like the $n$-th power
of some real number, in the sense that $\lim_{n\rightarrow \infty}f(n)^{1/n}$
exists. This confirms a conjecture of Cameron and Erd\"os, proposed in a paper
where they studied a number of similar problems, including the well known
"Cameron-Erd\"os os Conjecture" on counting sum-free subsets.
