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 N-[[4-(dimethylamino)phenyl]methyl]-N-ethyl-1-methyl-3-oxo-2,4-dihydroquinoxaline-6-carboxamide is given. What is its corresponding molecular formula?
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C21H26N4O2
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