import math

def termes(x, epsilon):
    limit = math.atanh(x)
    sn = 0
    lt = []
    n = 0
    tn = x
    while not (abs(sn - limit) < epsilon):
        sn = sn + tn
        lt.append(tn)
        n = n + 1
        tn = tn * x**2 * (2*n - 1) / (2*n + 1)
    return lt