You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (12aR)-9-(6-aminopyridin-3-yl)-7-(dimethylamino)-1,10,11-trihydroxy-12a-methoxy-3,12-dioxo-4a,5,5a,6-tetrahydro-4H-tetracene-2-carboxamide by IUPAC nomenclature, provide its molecular formula.
user
C27H28N4O7
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