(n+1)⁢Pn+1(λ)⁡(x;a,b)=2⁢((n+λ+a)⁢x+b)⁢Pn(λ)⁡(x;a,b)-(n+2⁢λ-1)⁢Pn-1(λ)⁡(x;a,b),