Bn(-z)={-(2/π)sin(12pπ)z-n/4(sin(ζ-14π)+|ζ|O(ζ-1)),|phz|2pπ-δ,n odd,(1/π)sin(pπ)z-n/4-ζ(1+O(ζ-1)),|phz|3pπ-δ,n even.