You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
7-[(4-ethylphenyl)methyl]-4-methyl-8-methylidene-2,5,7,11-tetrazatricyclo[7.4.0.02,6]trideca-1(9),5-diene The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H26N4
assistant