You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule identified by N-[(3aR,7aS)-7a-methyl-1,3-dioxo-4,7-dihydro-3aH-isoindol-2-yl]pyridine-4-carboxamide ?
user
C15H15N3O3
assistant