R-a⁡(b;z)=1B⁡(a,a′)⁢∫0∞ta′-1⁢∏nj=1(t+zj)-bj⁢ⅆ⁡t=1B⁡(a,a′)⁢∫0∞ta-1⁢∏nj=1(1+t⁢zj)-bj⁢ⅆ⁡t,