((1-z)⁢ⅆⅆ⁡z⁡(1-z))n⁢(zc-1⁢(1-z)b-c⁢F⁡(a,b;c;z))=(c-n)n⁢zc-n-1⁢(1-z)b-c+n⁢F⁡(a-n,b;c-n;z).