You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (2S,3aR,7aS)-1-(2-methylpropanoyl)-2,3,3a,4,5,6,7,7a-octahydroindole-2-carboxylic acid into its molecular formula.
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C13H21NO3
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