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