There is a series of monomials: the second power of X, the third power of negative 2x, the fourth power of 3x, and the fifth power of negative 4x. Their laws? 2008, the monomials of N? But it's three o'clock today

There is a series of monomials: the second power of X, the third power of negative 2x, the fourth power of 3x, and the fifth power of negative 4x. Their laws? 2008, the monomials of N? But it's three o'clock today

Xn=(-1)^(n+1)*n*X^(n+1)
X2008=-2008*X^2009