∫-∞∞ⅆ⁡tΓ⁡(a+t)⁢Γ⁡(b+t)⁢Γ⁡(c-t)⁢Γ⁡(d-t)=Γ⁡(a+b+c+d-3)Γ⁡(a+c-1)⁢Γ⁡(a+d-1)⁢Γ⁡(b+c-1)⁢Γ⁡(b+d-1),