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 (4R,5S)-2-[4-(4-fluorophenyl)piperazin-1-yl]-4-(furan-2-yl)-6-oxo-4,5-dihydro-1H-pyrimidine-5-carboxylate by IUPAC nomenclature, provide its molecular formula.
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C21H23FN4O4
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