Python pandas dataframe looping

Question

import pandas as pd
df2 = pd.DataFrame([])
for i in range(0,6):
df1 = pd.DataFrame([[i,i+1]], columns=['a','b'])
print(df2.append(df1))

Can anyone please let me that where am I making the mistake
I want the output as dataframe

a b
0 1
1 2
2 3
3 4
4 5
5 6
And it should be stored in the df2 dataframe

Answer 1

import pandas as pd
df2 =[]
for i in range(6):
df1 = [i, i+1]
df2.append(df1)

df2 = pd.DataFrame(df2, columns=['a','b'])
print(df2)