You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (5E)-4-but-3-enyl-5-ethylidene-3-[(Z)-1-[[(3Z,5E)-5-methoxyhepta-3,5-dien-2-ylidene]amino]prop-1-enyl]pyrrol-2-one by IUPAC nomenclature, provide its molecular formula.
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C21H28N2O2
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