[จูกัดเหลียง]

Merry Christmas and Happy New Year $2021$

$$\pi = \dfrac{1}{4\cdot 2021}\dfrac{4^{2021+\frac{1}{4}}\cdot 2021!}{3 \cdot 7\cdot 11 \cdot 15 \cdot 19\dots 8079}\int_{0}^{\frac{\pi}{4}}\dfrac{\cos^{2\cdot 2021-2}\theta+\sin^{2\cdot 2021-2}\theta\cdot \tan\theta}{\sqrt{\tan\theta}} \text{ } d\theta$$