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 (3R,7S,8aS)-3-(2-methylpropyl)-7-[(4-propan-2-ylphenyl)methylamino]-2,3,6,7,8,8a-hexahydropyrrolo[1,2-a]pyrazine-1,4-dione is given. What is its corresponding molecular formula?
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C21H31N3O2
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