You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-ethyl-N-[(3-fluorophenyl)methyl]-4-oxo-1,2,3,3a,5a,6,7,8,9,9a-decahydropyrazolo[1,5-a]quinoxaline-7-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H27FN4O2
assistant