Hℓ±⁡(η,ρ)=ⅇ±ⅈ⁢θℓ⁡(η,ρ)(2⁢ℓ+1)!⁢Γ⁡(-ℓ+ⅈ⁢η)⁢(∑k=0∞(a)k(2⁢ℓ+2)k⁢k!⁢(∓2⁢ⅈ⁢ρ)a+k⁢(ln⁡(∓2⁢ⅈ⁢ρ)+ψ⁡(a+k)-ψ⁡(1+k)-ψ⁡(2⁢ℓ+2+k))-∑k=12⁢ℓ+1(2⁢ℓ+1)!⁢(k-1)!(2⁢ℓ+1-k)!⁢(1-a)k⁢(∓2⁢ⅈ⁢ρ)a-k),