Prove 1p1 + 2 * (2P2) + 3 * (3p3) +. + n * (NPN) = (n + 1) P (n + 1) - 1

Prove 1p1 + 2 * (2P2) + 3 * (3p3) +. + n * (NPN) = (n + 1) P (n + 1) - 1

Let n = K be true, that is, 1 * 1! + 2 * 2! + 3 * 3! K * k! = (K + 1)! - 1, then n = K + 1 is 1 * 1! + 2 * 2!. + k * k! + (K + 1) * (K + 1)! = (K + 2)! - 1. By subtracting the two formulas, the left = (K + 1) * (K + 1)!, the right = (K + 2)! - (K + 1)! = (K + 1) * (K + 1)!. the left formula equals the right formula, that is, when n = K + 1, the conclusion is also true