w2⁢(z)=Γ⁡(2-c)⁢Γ⁡(c-a-b)Γ⁡(1-a)⁢Γ⁡(1-b)⁢w3⁢(z)+Γ⁡(2-c)⁢Γ⁡(a+b-c)Γ⁡(a-c+1)⁢Γ⁡(b-c+1)⁢w4⁢(z),