You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-hydroxy-N-[1-(2-phenoxyacetyl)pyrrolidin-3-yl]-8-azabicyclo[3.2.1]octane-8-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H27N3O4
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