Γ⁡(a+1)⁢ⅇ±π⁢ⅈ⁢a2⁢π⁢ⅈ⁢Γ⁡(-a,z⁢ⅇ±π⁢ⅈ)=∓12⁢erfc⁡(±ⅈ⁢η⁢a/2)+ⅈ⁢T⁡(a,η),