You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named [(2R)-2-[(2R)-2-(furan-2-yl)-2-hydroxyethyl]azepan-1-yl]-[(2R,5R)-5-methyloxolan-2-yl]methanone by IUPAC nomenclature, provide its molecular formula.
user
C18H27NO4
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