Does this series converge (1

Quote:

Originally Posted by buckeye1973

Hmm.. How about this..

Take as a given that $\left\{1 - \frac{\log n}{n}\right\}$ is an increasing sequence with $\lim_{n \to \infty} \left(1 - \frac{\log n}{n}\right) = 1$ . (It is true: see here.)

For $|r| < 1$ we know that

$\sum_{n=0}^\infty r^n = \frac{1}{1-r}$

but that same sum diverges for any other r.

Let $r \in (0,1)$ . Then, by definition of limit, there exists $N \in \mathbb{N}$ such that for each $n \geq N$ , $\left(1 - \frac{\log n}{n}\right) > r$ . Thus for any $r \in (0,1)$ , there are an infinite number of terms such that
$\left(1 - \frac{\log k}{k}\right)^k > r^k$ . Hence, $\sum\left(1 - \frac{\log n}{n}\right)^n$ is greater than any (monic) convergent geometric series, and is therefore divergent.

QED?

Anyone? I'm afraid that this post has had so many replies that nobody wants to read it, but I haven't got a usable answer. Plato gave a good hint maybe, but I don't follow it..

Does this series converge (1 - (log n)/n)^n