如何用vb求数列1+（1×2）+（1×2×3）+…+(1×2×3×…×n)的值。N由用户指定。

N=inputbox("请输入N的值：")
for i=1 to N
S=S+F(i)
next N
print S
private function F(byval x as integer) as Long
dim K as integer
F=1
for k=1 to x
F=F*k
next k
end function

s=1
n=inputbox("")
for i=1 to n
s=s*i
t=t+s
next i
print t