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 3-ethyl-N-[(2-methoxyphenyl)methyl]-N-methyl-2-oxo-1,3-benzothiazole-6-sulfonamide is given. What is its corresponding molecular formula?
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C18H20N2O4S2
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