You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named (1R,1aR,6bS)-3-chloro-1a,6b-dihydro-1H-cyclopropa[b][1]benzofuran-1-carboxylic acid;1-[(1R,1aR,6bS)-3-chloro-1a,6b-dihydro-1H-cyclopropa[b][1]benzofuran-1-yl]ethanone is given. What is its corresponding molecular formula?
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C21H16Cl2O5
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