You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(7E,9E,11E)-8-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-3-(1-ethylpiperidin-4-yl)pyrido[1,2-a]azocin-6-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C27H31N5O
assistant