You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 6-ethyl-N-[(2R)-2-(4-ethylpiperazin-1-yl)propyl]thieno[2,3-d]pyrimidin-4-amine by IUPAC nomenclature, provide its molecular formula.
user
C17H27N5S
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