You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
tert-butyl (2S,3aS,4S,7aS)-4-[tert-butyl(dimethyl)silyl]oxy-2-ethenyl-2,3,3a,4,5,7a-hexahydroindole-1-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H37NO3Si
assistant