You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule (1R,2R,4S)-2-ethyl-7-[3-(1H-indol-3-yl)propanoyl]-7-azabicyclo[2.2.1]heptane-2-carboxylic acid ?
user
C20H24N2O3
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