Sequence23 (2 points)
=====================

We define the following mathematical series:

.. math::
   & x_0  = 0.5 \\
   & x_i  = \frac{1}{i^2 \sqrt{i}} + x_{i-1},  \quad  i>0 \\

Write function :py:func:`sequence23` that takes two values, ``k`` and
``eps`` (both :class:`float`) and returns the summation
(:class:`float`) of the terms of this series until we reach the first
term which is equal to ``k`` with a tolerance ``eps``. This term will **not** be
included in the summation. We say that two values, :math:`a`,
:math:`b` are equal with a tolerance :math:`\epsilon` when they meet
the following condition: :math:`abs(a-b) < \epsilon`

Save this function in file ``sequence23.py``.

Examples:

.. literalinclude:: test-sequence23.txt
      :language: python
      :lines: 3-8

.. note::

   More tests are provided in file :download:`test-sequence23.txt`.