<<< native
[ EStyled TextBold [ EIdentifier "C" ]
, EDelimited
    "("
    ")"
    [ Right (EIdentifier "n")
    , Right (ESymbol Pun ",")
    , Right (EIdentifier "k")
    ]
, ESymbol Rel "="
, ESubsup
    (EStyled TextBold [ EIdentifier "C" ])
    (EIdentifier "k")
    (EIdentifier "n")
, ESymbol Rel "="
, ESub (EGrouped []) (EIdentifier "n")
, ESub (EStyled TextBold [ EIdentifier "C" ]) (EIdentifier "k")
, ESymbol Rel "="
, EDelimited
    "("
    ")"
    [ Right (EFraction NoLineFrac (EIdentifier "n") (EIdentifier "k"))
    ]
, ESymbol Rel "="
, EFraction
    NormalFrac
    (EGrouped [ EIdentifier "n" , ESymbol Ord "!" ])
    (EGrouped
       [ EIdentifier "k"
       , ESymbol Ord "!"
       , ESpace (1 % 6)
       , EDelimited
           "("
           ")"
           [ Right (EIdentifier "n")
           , Right (ESymbol Bin "\8722")
           , Right (EIdentifier "k")
           ]
       , ESymbol Ord "!"
       ])
]
>>> eqn
bold {C} left ( n , k right ) = {bold {C}} sub k sup n = {""} sub n {bold {C}} sub k = left ( n / k right ) = {n !} over {k ! ^ left ( n - k right ) !}