给你个公式∑(i=1到n)i^2=n(n+1)(2n+1)/61×2+2×3+3×4+.....+50×51=∑(i=1到50)[i(i+1)]=∑(i=1到50)i^2+∑(i=1到50)i=50(50+1)(50*2+1)/6+50(50+1)/2=44200
