You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (3S,4S)-1-(3-ethyl-5-methyl-1,2-oxazole-4-carbonyl)-4-methylpyrrolidine-3-carboxylic acid by IUPAC nomenclature, provide its molecular formula.
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C13H18N2O4
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