∫Vn1-∑k=1ntkzn+1-1⁢∏k=1ntkzk-1⁢ⅆ⁡tk=Γ⁡z1⁢Γ⁡z2⁢⋯⁢Γ⁡zn+1Γ⁡z1+z2+…+zn+1.