$(document).ready(function(){
lastBlock = $("#a1");
maxWidth = 180;
minWidth = 40;

$("ul.numbers li a").hover(
function(){
$(lastBlock).animate({width: minWidth+"px"}, { queue:false, duration:400 });
$(this).animate({width: maxWidth+"px"}, { queue:false, duration:400});
lastBlock = this;
}
);
});