You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 6-O-ethyl 7-O-phenacyl (1R,2S,4S,5S,6S,7S)-tricyclo[3.2.2.02,4]non-8-ene-6,7-dicarboxylate by IUPAC nomenclature, provide its molecular formula.
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C21H22O5
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