You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name 1-[(3aR,9bS)-6-methoxy-1,2,3a,4,5,9b-hexahydrobenzo[e]indol-3-yl]-2-cyclopentylethanone into its molecular formula.
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C20H27NO2
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