You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (R)-[1-(5,6-dimethylthieno[2,3-d]pyrimidin-4-yl)piperidin-4-yl]-phenylmethanol by IUPAC nomenclature, provide its molecular formula.
user
C20H23N3OS
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