You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[[1-(3-pyrrolo[2,3-c]pyridin-1-ylpropanoyl)piperidin-3-yl]methyl]pyrrolidin-2-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H26N4O2
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