var a:array[0..100000] of integer;
i,n,imax:integer;
begin
 n:=1;
 imax:=0;
 while n>0 do
  begin
    readln(n);
    if n=0 then exit;
      a[0]:=0;
      a[1]:=1;
    for i:=1 to n do
     begin
      a[2*i]:=a[i];
      a[2*i+1]:=a[i]+a[i+1];
     end;
  for i:=0 to n do
   if a[i]>=a[imax] then imax:=i;
 writeln(a[imax]);
 end;
end.

Why TLEX?

Try test
99 999
99 999
99 999
99 999
99 999
99 999
99 999
99 999
99 999
99 999
0
Calculation max once.
Now you calculate 2 time (main cicle and for search max).