Chudnovsky

import math;
n = int(input("Iterations: "));
summ = 0;
i = 0;
while (i <= n):
    summ = summ + (pow(-1,i)*math.factorial((6*i))*(545140134*i+13591409))/(math.factorial(3*i)*pow(math.factorial(i),3)*pow(pow(640320,3),i+0.5));
    i = i+1;
pi = 1/(12*summ);
print(pi);