Ok, in that case Python would be 0, 1, 3 and Julia 1, 2, 3. My point is that the example explicitly skips an index in the definition of a data frame for Python, but it doesn't for Julia.
df = pd.DataFrame( {'col_1': [11, 12, 13], 'col_2': [21, 22, 23]}, index=[0, 1, 3])