You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule 2-ethyl-3,10,13,20-tetrazapentacyclo[11.7.0.03,11.04,9.014,19]icosa-1(20),4,6,8,10,14,16,18-octaene into molecular formula.
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C18H16N4
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