μ N  = N 1   n        ( 76 )   MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacH8akY=wiFfYdH8Gipec8Eeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9s8qqaq=dirpe0xb9q8qiLsFr0=vr0=vr0dc8meaabaqaciaacaGaaeqabaqabeGadaaakeaaiiGacqWF8oqBdaWgaaWcbaacbeGae4Nta4eabeaakiabg2da9maalaaabaGae4Nta40aaSbaaSqaaiabigdaXaqabaaakeaacqWGUbGBaaGaaCzcaiaaxMaacqGGOaakcqaI3aWncqaI2aGncqGGPaqkaaa@3976@