You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2E,4Z,6E)-5,7,14,15-tetramethyltricyclo[8.7.0.011,15]heptadeca-2,4,6-triene by IUPAC nomenclature, provide its molecular formula.
user
C21H32
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