A first row transition metal with highest enthalpy of atomisation, upon reaction with oxygen at high temperature forms oxides of formula $$M_2O_n$$ (where $$n = 3, 4, 5$$). The 'spin-only' magnetic moment value of the amphoteric oxide from the above oxides is ______ BM (nearest integer). (Given atomic number: Sc: 21, Ti: 22, V: 23, Cr: 24, Mn: 25, Fe: 26, Co: 27, Ni: 28, Cu: 29, Zn: 30)