The line for which I am getting this error is:

u = Dx[0] + Dx[1] * (f - f0) + sum((2 * Dy_p(p + 1) + sum(Co(p, j) * DF.subs(f, 0) * DB1[j] for j in range(p + 1))) * (f - f0)**(p + 2) / sp.factorial(p + 2) for p in range(13))

I wish to get corrected code so that I can get the plot of Lie series solution of 2nd order differential equation obtained as equation of motion of restricted three body problem