You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 4-[[5-[(5-fluoro-2-oxo-1H-indol-3-ylidene)methyl]-2,4-dimethyl-1H-pyrrol-3-yl]methylamino]-N-hydroxybutanamide by IUPAC nomenclature, provide its molecular formula.
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C20H23FN4O3
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