You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (5R,8R,9S,10S,13S,14S,17S)-17-(1-hydroxyethyl)-10,13-dimethyl-1,2,4,5,6,7,8,9,11,12,14,15,16,17-tetradecahydrocyclopenta[a]phenanthren-3-one by IUPAC nomenclature, provide its molecular formula.
user
C21H34O2
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