@staticmethod
def b_n(n):
    """
        b(n) computation. This is the approximation of the exact solution to the relation, 2*incomplete_gamma_function(2n; b_n) = Gamma_function(2*n).
        :param n: the sersic index
        :return:
        """
    bn = 1.9992 * n - 0.3271
    return bn
