program M24
 implicit none
 integer::N=0,ishota=0,ishotb=0,s=0,f=0
 double precision::a=0,b=0
 read(*,*)N
 do ishota=1,N
  f=0
  do ishotb=1,ishota
   a=ishota/ishotb
   b=mod(ishota,ishotb)
   if(b==0)then
    f=f+1
   end if
  end do
  s=s+ishota*f
 end do
 print'(i0)',s
end program M24