
Imports System.Console
Module Module1
    Sub Main()
        Dim n As Integer = ReadLine()
        Dim ans As Int64
        For i = 1 To n
            ans += i * Yakusu(i)
        Next
        WriteLine(ans)
        ReadLine()
    End Sub
    Public Function Yakusu(ByVal k As Integer) As Int64
        Dim w As Int64 = Math.Round(Math.Sqrt(k))
        Dim r As Integer
        For i = 1 To w
            If k Mod i = 0 Then
                r += 1
            End If
        Next
        r *= 2
        If w ^ 2 = k Then
            r -= 1
        End If
        Return r
    End Function
End Module
