You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule N-(3,4-dihydro-2H-1,5-benzodioxepin-7-ylmethyl)-5-phenyl-[1,2,4]triazolo[1,5-a]pyrimidin-7-amine into molecular formula.
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C21H19N5O2
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