You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name ethyl 5-(4-methylphenyl)-10,10-dioxo-4H-pyrrolo[1,2-b][1,2,5]benzothiadiazepine-4-carboxylate into its molecular formula.
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C21H20N2O4S
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