program yakusuu

 implicit none
 integer::n,i,j,k,ans
 integer,allocatable::f(:)
 
 

 read*,n
 allocate(f(n))
 
 f=0
 
 do i=1,n
  do j=1,i
   if(mod(i,j)==0) then
    f(i)=f(i)+1
   end if
  end do
  !print*,f(i)
 end do

ans=0
 do k=1,n
  ans=ans+k*f(k)
 end do

 print*,ans

end program yakusuu