[Plot]

> odd*2-periodic*extension*of*f(x) = x^2

[Plot]

> 2*(-4+Pi^2)*sin(Pi*x)/(Pi^3)-sin(2*Pi*x)/Pi+2*(-4+9*Pi^2)*sin(3*Pi*x)/(27*Pi^3)

[Plot]

> 2*(-4+Pi^2)*sin(Pi*x)/(Pi^3)-sin(2*Pi*x)/Pi+2*(-4+9*Pi^2)*sin(3*Pi*x)/(27*Pi^3)-sin(4*Pi*x)/(2*Pi)+2*(-4+25*Pi^2)*sin(5*Pi*x)/(125*Pi^3)