It's possible to get this done using seaborn.lineplot() but it involves some additional work of converting numpy arrays to pandas dataframe. Here's a complete example:
# imports
import seaborn as sns
import numpy as np
import pandas as pd
# inputs
In [41]: num = np.array([1, 2, 3, 4, 5])
In [42]: sqr = np.array([1, 4, 9, 16, 25])
# convert to pandas dataframe
In [43]: d = {'num': num, 'sqr': sqr}
In [44]: pdnumsqr = pd.DataFrame(d)
# plot using lineplot
In [45]: sns.set(style='darkgrid')
In [46]: sns.lineplot(x='num', y='sqr', data=pdnumsqr)
Out[46]: <matplotlib.axes._subplots.AxesSubplot at 0x7f583c05d0b8>
And we get the following plot:
