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 5-[(4-ethylphenyl)diazenyl]-2-hydroxy-1-(2-hydroxypropyl)-4-methyl-6-oxopyridine-3-carbonitrile is given. What is its corresponding molecular formula?
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C18H20N4O3
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