SymPy

      >>> from sympy import Symbol, cos
      >>> x = Symbol('x')
      >>> e = 1/cos(x)
      >>> print e.series(x, 0, 10)
      1 + (1/2)*x**2 + (5/24)*x**4 + (61/720)*x**6 + (277/8064)*x**8 + O(x**10)
    

      In [1]: (1/cos(x)).series(x, 0, 10)
      Out[1]:
      2      4       6        8
      x    5*x    61*x    277*x
      1 + ── + ──── + ───── + ────── + O(x**10)
      2     24     720     8064