How can I assign a name to the 'intersection' of index and columns in a pandas dataframe?

Question

If I create a dataframe and than generate a pivot table from it, it keeps appearing a string in the upper left "cell" of the resulting table, like below. In this example it appears the string "n":

import pandas as pd
df = pd.DataFrame({'col1':['a','a','b','b','c','c'],
               'col2':['str_a1','str_a2','str_b1','str_b2','str_c1','str_c2']})
df2 = df.assign(n=df.groupby('col1').cumcount()).pivot(index='col1',columns='n',values='col2').reset_index()
df2

n col1       0       1
0    a  str_a1  str_a2
1    b  str_b1  str_b2
2    c  str_c1  str_c2

If I create the dataframe directly like below, it appears nothing. How can I include the "n" in this second option and how can I remove the "n" from the option above?

df3 = pd.DataFrame({'col1':['a','b','c'],
                '0':['str_a1','str_b1','str_c1'],
                '1':['srt_a2','str_b2','str_c2']})
df3

  col1       0       1
0    a  str_a1  srt_a2
1    b  str_b1  str_b2
2    c  str_c1  str_c2

Answer 1

I got the answer by 'looking' at the dataframe 'horizontally' instead of 'vertically'. The 'n' that I was mentioning above was not the index name as splash58 pointed out. I must say that I used to think this way.

Than I noticed that the 'n' was in the same line as the other columns names's. Therefore it must be the name of the columns index.

In fact, if you do:

import pandas as pd
df = pd.DataFrame({'col1':['a','a','b','b','c','c'],
               'col2':['str_a1','str_a2','str_b1','str_b2','str_c1','str_c2']})
df2 = df.assign(n=df.groupby('col1').cumcount()).pivot(index='col1',columns='n',values='col2').reset_index()
print(df2)

you get:

n col1       0       1
0    a  str_a1  str_a2
1    b  str_b1  str_b2
2    c  str_c1  str_c2

After this, if you do:

df2.columns.name

you get:

'n'