You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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What is the molecular formula of the compound with this IUPAC name (4aS,4bR,10bS,12aS)-9-bromo-12a-ethyl-8-hydroxy-2,3,4,4a,4b,5,6,10b,11,12-decahydrochrysen-1-one ?
user
C20H25BrO2
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