SubArea: CombinatoricsLevel: BProject ID: 9000140504Accepted: 1Clonable: 0Easy: 0Simplify for n∈N, n≥2. n⋅(n−2)!(n−1)⋅n!1(n−1)2(n2−2n)!(n2−n)!n+1n−1(n−2)!(n−1)!