You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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3-(1-methylpyrrolidin-2-yl)-N-(2-pyridin-3-ylethyl)imidazo[1,5-a]pyridine-1-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
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C20H23N5O
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