Const
 Eps=0.0001;

Var
 x,y:Real;
 i:Byte;

Function S(z:real):real;
var
 a,T:real;
 n:byte;
begin
 a:=3.0/(z*2);
 n:=2;
 T:=a;
 Repeat
  a:=a/((n-1)*(n+1));
  Inc(n);
  a:=a*(n-1)*(n+1)/(z*n);
  T:=T+a;
 Until Abs(a)<Eps;
 S:=T;
end;

Begin
 Writeln('  x         y');
 for i:=4 to 20 do
  begin
   x:=i/2;
   y:=S(x);
   Writeln(x:4:1, y:12:5);
  end;
 Readln
End.