Tony Lezard asked me the following question which seemed like it should not be too hard but which I did not immediately see how to answer.  Define $f(n,k)$ recursively by $f(1,k) = 1$ and

$$f(n,k) = \frac{1}{1-(1-1/k)^n} \sum_{r=1}^{n-1} \binom{n}{r} \left(\frac{1}{k}\right)^{n-r} \left(1 - \frac{1}{k}\right)^r f(r,k).$$

What can we say about $\lim_{n\to\infty} f(n,k)$?  Even the special case $k=2$ would be interesting:

$$f(n,2) = \frac{1}{2^n-1} \sum_{r=1}^{n-1} \binom{n}{r} f(r,2).$$