new; cls;
n=6; r=3;


x=zeros(n,1);
do while not x==ones(n,1);
   x=recbin(x);
   if sumc(x)==r;
      print/rz x';    /* or use this x as some index number vector in your program */
   endif;
endo;

proc recbin(x);
   local n,j;
   n=rows(x);
   x[n]=x[n]+1;
   j=n;
   do until j==0;
      if x[j]==2;
         x[j]=0;
         x[j-1]=x[j-1]+1;
      endif;
      j=j-1;
   endo;
   retp(x);
endp;