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-(3-methylphenyl)-N-(4-oxo-2,3,3a,5-tetrahydro-1H-pyrrolo[1,2-a]quinoxalin-2-yl)methanesulfonamide is given. What is its corresponding molecular formula?
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C19H21N3O3S
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