How to simplify SUM(k=0,inf,x^k/k!) ?

[Marcus von Cube, Germany]

Hi

I'm playing around with various CAS implementations and found that it's no so easy to find the simplification for the well known infinite sum:

 oo

----'

\     xk

 |   ---

/     k!

----'

 k=0

Is this possible with the 49g+ or any other Erable based CAS?

The Voyage 200 does not do it, while Derive on the PC knows the correct result.

Marcus

[Crawl]

I don't think the 49G+ can do it.

It can at least find sum(n = 1, inf, 1/n^x) for even x.

And it can find various closed forms of finite sums (the geometric series, 1 + 2 + 3 + ... + n = n(n+1)/2, sums of reciprocal triangle numbers, more complicated cases), too.