You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 3-[8-amino-6-(4-ethylpyridin-3-yl)-2,7-naphthyridin-3-yl]-1,1-dimethylurea;ethane into molecular formula.
user
C20H26N6O
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