A~n=-(n+2⁢ℜ⁡(a+b)-1)⁢(n+a+a¯)⁢(n+a+b¯)(2⁢n+2⁢ℜ⁡(a+b)-1)⁢(2⁢n+2⁢ℜ⁡(a+b)),