What is the running time of the following piece of code ?

for(i=n; i>0; i/=2)
{
     for(j=1; j<n; j*=2)
     {
          for(k=0; k<n; k+=2)
               sum=sum+1;
     }
}

Difficulty level
This exercise is mostly suitable for students 
O(n*(log(n))^2)
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