∵ x²+x+1 = 0
x^2013+x^2012+x^2011+…+x^3+x²+x+1
= (x²+x+1)x^2011 + (x²+x+1)x^2008 + (x²+x+1)x^2005 +…… + (x²+x+1)x^4 + (x²+x+1)x +1
= 1