You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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4-(2-ethyl-6-phenyl-1,2-dihydro-[1,2,4]triazolo[1,5-a]pyrimidin-5-yl)benzaldehyde is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H18N4O
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