vsota
5 + (4*(1/(2*n^2) - 1/(2*n)))/125 + (8*(1/(6*n^3) - 1/(2*n^2) + 1/(3*n)))/
  3125 + 2/(5*n)
-1/4
(1 - 6*x)/36 + C[1]/E^(2*x) + E^(3*x)*C[2]