Indiana,
В массиве имён нет необходимости
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<script language="JavaScript" type="text/javascript">
a=[];
a[0]=100;
a[1]=350;
a[2]=450;
function start(){
for (i= 0; i < a.length; i++){
document.getElementById('c'+i).innerHTML =a[i];
}}
</script>
</head>
<body onload="start()">
<div id="c0"></div>
<div id="c1"></div>
<div id="c2"></div>
</body>
</html>