An interesting problem of polynomials 
In the polynomial
  $$
(x-1)(x^2-2)(x^3-3) \ldots (x^{11}-11)
$$
  what is the coefficient of $x^{60}$? 

I've been trying to solve this question since a long time but I couldn't. I don't know whether opening the brackets would help because that is really a mess. I have run out of ideas. Would someone please help me to solve this question? 

Hint : $1+2+3 +...+11= \frac {11×12}{2} =66 $ so we must find how we can construct number $6=6+0=5+1=4+2=3+3=1+2+3$ and note that $3+3$ impossible. 
