You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named methyl (1S,2R,4R,5S)-4-methylspiro[3,8-dioxatricyclo[3.2.1.02,4]octane-6,1'-cyclopentane]-2-carboxylate by IUPAC nomenclature, provide its molecular formula.
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C13H18O4
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