from string import ascii_letters

import numpy as np
import pandas as pd

df = pd.DataFrame({letter: [1, 2, 3] for letter in ascii_letters[:14]})

df2 = pd.pivot_table(
    df,
    values=["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n"],
    columns=["a"],
    aggfunc={
        "a": np.sum,
        "b": np.sum,
        "c": np.sum,
        "d": np.sum,
        "e": np.sum,
        "f": np.sum,
        "g": np.sum,
        "h": np.sum,
        "i": np.sum,
        "j": np.sum,
        "k": np.sum,
        "l": np.sum,
        "m": np.sum,
        "n": np.sum,
    },
)