Pn(λ)⁡(x;ϕ)=(2⁢λ)nn!⁢ⅇⅈ⁢n⁢ϕ⁢F12⁡(-n,λ+ⅈ⁢x2⁢λ;1-ⅇ-2⁢ⅈ⁢ϕ).