Question: simplify results

Hi everybody;

I have question about my calculation. my questions maybe looks like very simple.

>restart:
>lambda:=-1; alpha:=0.5;  N:=1;  m:=ceil(alpha);

                             lambda := -1
                             alpha := 0.5
                                N := 1
                                m := 1

> u[0]:=0;      #initial conditions

                              u[0] := 0

> for i from 0 to N do
> DI1:=simplify((1/GAMMA(m-alpha))*int((x-t)^(m-alpha-1)*diff(u[i],[t$m]),t=0..x));
> DI1:=subs(x=t,%);
> DI2:=DI1-(t^(1/2)/evalf(Pi)^(1/2))*(u[i]+1)^2;
> DI2:=subs(x=t,%);
> u[i+1]:=u[i]+simplify(int((1/GAMMA(alpha))*lambda*(x-t)^(alpha-1)*DI2,t=0..x));
> u[i+1]:=subs(x=t,%);
> end do:

> v:=subs(t=x,u[i]);

                                                                  3                          2
       v := 0.5000000000 x + 0.07812499996 x  + 0.3749999999 x

Here I want to get the results in this form   1/2x+3/8x^2+15/192x^3  also for N=0, I vant to get 1/2x=(1/pi^2)*(Gamma(3/2)/Gamma(2))*x, I know for this form I have to use "Gamma" notation. 

Also, as you see in above, after DI1 and DI2 I use subs command for using them again in loop. Is there any easy way to do this

Thanks for your kindly help.

Agim