You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule methyl 3-[2-(tert-butylamino)-2-oxoethyl]-2,5-dimethyl-4-oxothieno[2,3-d]pyrimidine-6-carboxylate into molecular formula.
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C16H21N3O4S
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