You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named N-[(2S,8aS)-8a-(pyrrolidine-1-carbonyl)-2,3,5,6,7,8-hexahydro-1H-indolizin-2-yl]-3-(2-ethylimidazol-1-yl)propanamide is given. What is its corresponding molecular formula?
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C21H33N5O2
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