题目有一列按照一定规律写出的单项式:3x3x3x,−6x2-6x^{2}−6x2,9x39x^{3}9x3,−12x4-12x^{4}−12x4,15x515x^{5}15x5,⋯\cdots⋯,则这列单项式中的第202420242024个为______.知识点：单项式章节：未标注
