math.vbs 自然数n的n次方的的和或积的级数

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