$ cat file
2013113098

$ cat serial.sh

  awk '

BEGIN{
         OFS="\t"
         printf RS OFS "Enter Year till which you want to generate serial number : "
         getline stop < "-"
         printf OFS "Enter Output Filname :  "
         getline out < "-" 
         nonleap = "31,28,31,30,31,30,31,31,30,31,30,31"
         leap     = "31,29,31,30,31,30,31,31,30,31,30,31"
         split(nonleap,NLP,",")
         split(leap,LP,",")
         if(!stop){printf RS "\t" "No User Input...Exiting" RS RS;exit }
     }

function serial(start,m,d,y){
                                   for(s=start;s<=100;s++)    
                                               if(out){
                                                       print y sprintf("%.2d",m) sprintf("%.2d",d) sprintf("%.3d",s) >out
                                                      } 
                                              else
                                                     {
                                                        print y sprintf("%.2d",m) sprintf("%.2d",d) sprintf("%.3d",s)
                                                     }
                            }

    {
        ser=substr($1,8,10)
        day=substr($1,7,2)
        mon=substr($1,5,2)        
        year=substr($1,0,4)

        if(stop~/[A-Za-z]/){print "Year should be Integer...Exiting" RS;exit}
        if(stop%1!=0){print "Year cannot be float...Exiting" RS;exit}
        if(stop<year){print "Year should be Equal or Greater than  Existing Serial Number...Exiting" RS;exit}

        f=1
        for(y=year;y<=stop;y++){
                mon=(f==1)?mon:1
                
        f=0
                g=1        
                for(m=mon;m<=12;m++)
                    {
                        dend=((y%4==0) || (y%100==0) || (y%400==0))?LP[m]:NLP[m]
                        day=(g==1)?day:1
                        ser=(g==1)?ser:0
                        for(day=day;day<=dend;day++){serial(ser,m,day,y)}
                g=0
                    }                
                                 }
            
     }' file

$ sh serial.sh

  Enter Year till which you want to generate serial number : 2013
  Enter Output Filname :  test.txt

20131130098
20131130099
20131130100
20131201000
20131201001
20131201002
20131201003
20131201004
20131201005
20131201006