(1-z)y⁢F12⁡(y-N,y+γ+1-δ-N;z)=∑n=0N(γ+1)n⁢(-N)n(-δ-N)n⁢n!⁢Rn⁡(y⁢(y+γ+δ+1);γ,δ,N)⁢zn.