Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
formally [ˈfɔːməlɪ] adv форма́льно; (behave) церемо́нно
to be formally invited получа́ть (получи́ть*perf) официа́льное приглаше́ние
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.