You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 4-amino-3-benzyl-1-[(2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)oxolan-2-yl]-4H-pyrimidin-2-one by IUPAC nomenclature, provide its molecular formula.
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C16H21N3O5
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