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 propyl 4-[(3aR,7aR)-1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl]benzoate is given. What is its corresponding molecular formula?
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C18H21NO4
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