R-a⁡(b;z)=4⁢Γ⁡(b1+b2+b3)Γ⁡(b1)⁢Γ⁡(b2)⁢Γ⁡(b3)⁢∫0π/2∫0π/2(∑j=13zj⁢lj2)-a⁢∏j=13lj2⁢bj-1⁢sin⁡θ⁢ⅆ⁡θ⁢ⅆ⁡ϕ,