编写函数fun，计算下列多项式：s=1+x+x**2/2!+x**3/3!+•••+x**n/n!

Sure, I can help you with that! Here is the function:

def fun(x, n):
    s = 1
    fact = 1
    for i in range(1, n+1):
        fact *= i
        s += (x ** i) / fact
    return s

Simply pass in the value of `x` and the number of terms `n` you want to use in the approximation. The function will return the value of the sum of the series.

Hope this helps!