You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-(3,15-dimethyl-8,11-dioxa-3-azoniatetracyclo[7.6.1.02,7.012,16]hexadeca-1(15),2,4,6,9,12(16),13-heptaen-6-yl)-2,2-dimethylpropanenitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H19N2O2+
assistant