You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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N-(2-piperidin-1-ylethyl)-3-(1,3,5,7-tetramethyl-2,4-dioxopyrido[2,3-d]pyrimidin-6-yl)propanamide is the IUPAC name of a molecule. Please give its molecular formula.
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C21H31N5O3
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