To get the 144 combinations I used the logic in tokenize.py:

import re

def _combinations(*l):
    return set(
        x + y for x in l for y in l + ("",) if x.casefold() != y.casefold()
    )

_strprefixes = (
    _combinations('r', 'R', 'f', 'F') | _combinations('r', 'R', 'b', 'B') | {'u', 'U', 'ur', 'uR', 'Ur', 'UR'}
)

triple_quoted = (
    {"'''", '"""'} | {f"{prefix}'''" for prefix in _strprefixes} | {f'{prefix}"""' for prefix in _strprefixes}
)
single_quoted = (
    {"'", '"'} | {f"{prefix}'" for prefix in _strprefixes} | {f'{prefix}"' for prefix in _strprefixes}
)

all_combinations = _strprefixes | single_quoted | triple_quoted

print(' '.join(list(all_combinations)))

print(len(all_combinations))