12⁢π⁢ⅈ⁢Γ⁡(a)⁢Γ⁡(b)⁢Γ⁡(c-a)⁢Γ⁡(c-b)⁢∫-ⅈ⁢∞ⅈ⁢∞Γ⁡(a+t)⁢Γ⁡(b+t)⁢Γ⁡(c-a-b-t)⁢Γ⁡(-t)⁢(1-z)t⁢ⅆ⁡t,