You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(2-methylpropan-2-yl)oxy]-4,5,6,7,8,9-hexahydrocycloocta[b]thiophene-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C15H23NO2S
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