Finding the sum of 2^n / n!

1. Aug 5, 2007

kj13529

I need to find the sum of 2^n/n! from n=2 to infinity, i know that it converges to e^x but how do i find the sum?

2. Aug 5, 2007

Kummer

It is e^2.
Since x^n/n! sums to e^x substitute x=2 to get answer.

3. Aug 5, 2007

kj13529

Thanks, it was so simple -.-