Bi⁡z=12⁢π⁢∫-∞∞⁢ⅇπ⁢ⅈ/3exp⁡13⁢t3-z⁢t⁢ⅆ⁡t+12⁢π⁢∫-∞∞⁢ⅇ-π⁢ⅈ/3exp⁡13⁢t3-z⁢t⁢ⅆ⁡t.