import math

def calc_term(a, b, x):
    return round( abs( (a + math.sin(x)) / (2*math.exp(b*x))), 4)

def sum3eventerms(a, b, x0):
    s = x = x0
    x = calc_term(a, b, x)
    x = calc_term(a, b, x)
    s += x
    x = calc_term(a, b, x)
    x = calc_term(a, b, x)
    s += x
    return round(s, 3)

def loop(a, b, x0, n):
    s = x = x0
    while n > 0:
        x = calc_term(a, b, x)
        s += x
        print(x, s)
        n -= 1
    print(round(s, 2))
    print('ciao')