You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name 5-(2-methylpyridin-3-yl)-3-[(1R,3R,8S)-3-phenyl-2,3,5,6,7,8-hexahydro-1H-pyrrolizin-1-yl]-1,2,4-oxadiazole into its molecular formula.
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C21H22N4O
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