You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named [(4R,7S,7aR,12bS)-9-methoxy-3-methyl-2,4,4a,7,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-yl]oxy-trimethylsilane by IUPAC nomenclature, provide its molecular formula.
user
C21H29NO3Si
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