You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-[(2R,3R,3aS)-3-hydroxy-3-(3-hydroxy-3-methylpent-4-enyl)-3a,7,7-trimethyl-1,2,4,5,6,7a-hexahydroinden-2-yl]ethanone by IUPAC nomenclature, provide its molecular formula.
user
C20H34O3
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