在python中，'int'对象不是可调用的错误

I'm getting this error:

我得到这个错误:

Traceback (most recent call last):
  File "C:\Users\George\Desktop\ex3.py", line 15, in <module>
    s=s+d*2(-1/6.)*(u-1)*(u-2)*(u+2)*(u-4)
TypeError: 'int' object is not callable
Traceback