# Summation and integration of 1/x factorial

### Summation and integration of 1/x factorial

How to prove this?
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### Re: Summation and integration of 1/x factorial

The factorial is only defined for integers so what do you mean by "x!"?

If your sum is over the no-negative integers then $$\sum_{n=0}^\infty \frac{1}{n!}= e$$ but in the integral, x cannot be an integer.
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