You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 3-[2-[(4aR,8aS)-3,4,4a,5,6,7,8,8a-octahydro-1H-isoquinolin-2-yl]-2-oxoethyl]-5,6-dimethylthieno[2,3-d]pyrimidin-4-one by IUPAC nomenclature, provide its molecular formula.
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C19H25N3O2S
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