U⁡(a,b,z)Γ⁡(c)⁢Γ⁡(c-b+1)=z1-c2⁢π⁢ⅈ⁢∫-∞(0+)ⅇz⁢t⁢t-c⁢F12⁡(a,c;a+c-b+1;1-1t)⁢ⅆ⁡t,