You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (6S,8S,9S,10R,11S,13S,14S,17S)-6,11-dihydroxy-17-(2-hydroxyacetyl)-10,13-dimethyl-1,2,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-3-one by IUPAC nomenclature, provide its molecular formula.
user
C21H30O5
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