точнее

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>TEST</title></head><body>
<p align="center">
"<iframe src="iframe1"></iframe>"
пауза3с
"<iframe src="iframe2"></iframe>"
пауза3с
"<iframe src="iframe_etc"></iframe>"
</p></body></html>