linfo2335-programming-paradigms/project-3/regex/code/code2177.py

def approx_pi(i):        
    if i == 0:
        return 4
    else:
        if i == 1:
            return 2.666666666
        else:
            if i == 2:
                return 3.46666666
            else:
                if i == 3:
                    return 2.8952381
                else:
                    pi = 0
                    for j in range(i+1) :
                        pi += (((-1)**pi) / ((2*pi)+1))
                        return(4*pi)