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 1-[(3aR)-4-(6-bromo-1,3-benzodioxol-5-yl)-2,3,3a,4,5,9b-hexahydrofuro[3,2-c]quinolin-8-yl]ethanone is given. What is its corresponding molecular formula?
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C20H18BrNO4
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