You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named N-tert-butyl-4-(4-oxidopyrazin-4-ium-2-yl)-11-oxa-3,4-diazatricyclo[6.2.1.02,6]undeca-2,5-diene-5-carboxamide by IUPAC nomenclature, provide its molecular formula.
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C17H21N5O3
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