参考自：https://www.zhihu.com/question/402311979
由
\[\frac{\pi^4}{90}={\textstyle \sum_{n=1}^{\infty }} \frac{1}{n^4}
\]
得到：
\[\pi =\sqrt[4]{ ({\textstyle \sum_{n=1}^{\infty }} \frac{1}{n^4} )\cdot 90}
\]
import math as m
from tqdm import trange#进度条
#求pi
N=10000000
num = 0
# for i in range(N):
# num += 1/((2*i+1)**2)
# pi=m.sqrt(num*8)
# print(pi)
for i in trange(N):
num += 1/((i+1)**4)
pi=m.pow(num*90,0.25)
print(pi)
