mputes an initial approximation to the square of the `k`-th
(positive) root :math:`x_k` of the Hermite polynomial :math:`H_n`
of order :math:`n`. The formula is the one from lemma 3.1 in the
original paper. The guesses are accurate except in the region
near :math:`\sqrt{2n + 1}`.

Parameters
----------
n : int
    Quadrature order
k : ndarray of type int
    Index of roots to compute

Returns
-------
xksq : ndarray
    Square of the approximate roots

See Also
--------
initial_nodes
roots_hermite_asy
rœ