Bi′⁡(-z)∼z1/4π⁢(cos⁡(ζ-14⁢π)⁢∑k=0∞(-1)k⁢v2⁢kζ2⁢k+sin⁡(ζ-14⁢π)⁢∑k=0∞(-1)k⁢v2⁢k+1ζ2⁢k+1),