var WhichSequence = 1;
var FirstSequence = 1;
var LastSequence = 5;

function InitialSequence(){
   var InitialObj = document.getElementById('Sequence' + FirstSequence);
    InitialObj.style.visibility = "visible";
  }

function ChangeSequence(){
  var Id1 = "";
  var Id2 = "";

  if(WhichSequence >= LastSequence)
    WhichSequence = 0;

  WhichSequence++;

  Id1 = "Sequence" + WhichSequence;
  if(WhichSequence == FirstSequence)
    Id2 = "Sequence" + LastSequence;
  else
    Id2 = "Sequence" + (WhichSequence - 1);

  //window.alert(Id1 + "-" + Id2);

  var ObjId1 = document.getElementById(Id1);
  ObjId1.style.visibility = "visible";

  var ObjId2 = document.getElementById(Id2);
  ObjId2.style.visibility = "hidden";
}