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Under IUPAC nomenclature, a molecule named ethyl 4-[2-[[3-(2,4-dimethoxyphenyl)-[1,2,4]triazolo[4,3-b]pyridazin-6-yl]oxy]ethylamino]-4-oxobutanoate is given. What is its corresponding molecular formula?
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C21H25N5O6
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