You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 5-[[(3aR,7aS)-1,2,3,3a,4,6,7,7a-octahydropyrrolo[3,2-c]pyridin-5-yl]methyl]-2-(2,6-dioxopiperidin-3-yl)isoindole-1,3-dione by IUPAC nomenclature, provide its molecular formula.
user
C21H24N4O4
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