∫1/(1+x^7)dx
=1/7*sin(3*π/14)*log(x^2+2*x*sin(3*π/14)+1)
-1/7*sin(π/14)*log(x^2-2*x*sin(π/14)+1)
-1/7*cos(π/7)*log(x^2-2*x*cos(π/7)+1)
+1/7*log(x+1)
+2/7*sin(π/7)*atan(csc(π/7)*(x-cos(π/7)))
+2/7*cos(3*π/14)*atan(sec(3*π/14)*(x+sin(3*π/14)))
+2/7*cos(π/14)*atan(sec(π/14)*(x-sin(π/14)))+C