通项为自然数n的n次方的的和或积的级数，求和或积的表达式。

代码如下:

dim n,m

n=inputbox("input a number:","recursion")

m=factorial ( n )

if n<0 then msgbox "must be input a number bigger 0."

elseif n=0 then msgbox "0"&"!"&"is:"&"0"

elseif n>0 then msgbox n&"is:"&m

rem how to done not input and press sure case.

end if

Function Factorial (N)

If N <= 1 Then Factorial = 1

Else Factorial = Factorial(N - 1)*n^n

End If

End Function