I have a Vf page which display account object records. In this vf page each and every record have a button called Edit. If we click on Edit button it should be take us to detailed edit page respected record. For more clearance see my pictures which i uploded. 



To achive this process, I have developed following VF page.

<apex:page Controller="Redirect_Main2" action="{!Redirect_Main}">
    <apex:form >
        <apex:pageBlock >
            <apex:pageBlockTable value="{!accs}" var="a" >
                <apex:column value="{!a.Id}"/>
                <apex:column value="{!a.Name}"/>
                <apex:column value="{!a.Phone}"/>
                <apex:column value="{!a.Industry}"/>
                <apex:column id="two">
                    <apex:commandButton value=" Edit " onclick="window.open('/{!a.id}')" reRender="two"/>
<!--/e?retURL=%2F{!a.id}&_CONFIRMATIONTOKEN=VmpFPSxNakF4Tmkwd055MHlPVlF3T1Rvek5qb3dPQzQ0TnpaYSxvTFl3eklmdmNBcjl6RlVDeDRWUnBtLE9XWTJNbU01&common.udd.actions.ActionsUtilORIG_URI=%2F{!a.id}%2Fe')" reRender="two"/>
   -->             </apex:column>
            </apex:pageBlockTable>
        </apex:pageBlock>
    </apex:form>
</apex:page>

public class Redirect_Main2 {

   public List<Account> accs { get; set; }
    public PageReference Redirect_Main(){
        accs = [select id,name,phone,Industry from account];       
        return null;
     }
}

But this is taking me to detailed page of the record but not edit page. Please tell me neccessary actions which i need to take.

Thanking you
KS Kumaar