You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 7-[[4-methoxy-3-[(2-methylimidazol-1-yl)methyl]phenyl]methyl]-2,5,6,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazin-3-one by IUPAC nomenclature, provide its molecular formula.
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C18H22N6O2
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