erences
----------
.. [1] R. L. Graham, D. E. Knuth and O. Patashnik, "Concrete
    Mathematics: A Foundation for Computer Science," Addison-Wesley
    Publishing Company, Boston, 1989. Chapter 6, page 258.

.. [2] Temme, Nico M. "Asymptotic estimates of Stirling numbers."
    Studies in Applied Mathematics 89.3 (1993): 233-243.

Examples
--------
>>> import numpy as np
>>> from scipy.special import stirling2
>>> k = np.array([3, -1, 3])
>>> n = np.array([10, 10, 9])
>>> stirling2(n, k)
array([9330.0, 0.0, 3025.0])

z'Argument `N` must contain only integersz'Argument `K` must contain only integers