You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 2-[(3'aR)-7'-acetyl-6'-methylspiro[1,3-dioxolane-2,1'-3,4,5,6,7,7a-hexahydro-2H-indene]-3'a-yl]-4,4-dimethylhexa-1,5-dien-3-one by IUPAC nomenclature, provide its molecular formula.
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C22H32O4
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