# How to sum this series

1. Nov 27, 2009

### zli034

1. The problem statement, all variables and given/known data
I just trying to sum this series, 1/(n!*n) n from 1 to infinity. also similar 1/(n!*n^2)

2. Relevant equations

$$\sum\frac{1}{(n!*n)}$$
$$\sum\frac{1}{(n!*n^2)}$$

3. The attempt at a solution
I know$$\sum\frac{1}{n!}=e$$
$$\sum\frac{1}{n}=ln$$

My math technique is rusty, can any one help? thanks in advance. ciao

2. Nov 27, 2009

### Dick

The sum of 1/n isn't ln. It diverges. And both of those sums involve nasty non-elementary functions. I only know this because I looked them up. Why do you think you have to evaluate them exactly? A numerical approximation to both converges very rapidly.

3. Nov 28, 2009

### zli034

Thanks. I am doing study on statistics. On some topic I have sum up probabilities of infinite number of events. I have done numberical approximation with excel, and the result is equivalent to a specific event. I was trying to show why.