You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named [(5R)-5-[(2R)-but-3-en-2-yl]-4-methylidenecyclopenten-1-yl] (1R,3R)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropane-1-carboxylate by IUPAC nomenclature, provide its molecular formula.
user
C20H28O2
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