12⁢π⁢ⅈ⁢Γ⁡(a)⁢Γ⁡(b)⁢∫-ⅈ⁢∞ⅈ⁢∞Γ⁡(a+t)⁢Γ⁡(b+t)⁢Γ⁡(-t)Γ⁡(c+t)⁢(-z)t⁢ⅆ⁡t,