[lmikle]

Код:

const
  S : String = '123456';
var
  I : Integer;
  Buf : String;
begin
  For I := 1 To Length(S) div 2 Do
    Begin
      Buf := '|' + S[i];
      If I*2 <= Length(S) Then Buf := Buf + '|' + S[I*2];
      Memo1.Lines.Add(Buf);
    End;
end;