You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named ethyl (6S)-2-(2,2-dimethylpropanoylamino)-6-ethyl-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate by IUPAC nomenclature, provide its molecular formula.
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C18H27NO3S
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