import sys

import numba



read = sys.stdin.buffer.read

readline = sys.stdin.buffer.readline

readlines = sys.stdin.buffer.readlines



@numba.njit

def main(N):

    x = 0

    for a in range(1, N+1):

        for b in range(1, N//a+1):

            x += a*b

    return x



N = int(read())

print((main(N)))

import sys

import numba



read = sys.stdin.buffer.read

readline = sys.stdin.buffer.readline

readlines = sys.stdin.buffer.readlines



@numba.njit('(i8,)', cache=True)

def main(N):

    x = 0

    for a in range(1, N+1):

        for b in range(1, N//a+1):

            x += a*b

    return x



N = int(read())

print((main(N)))

import sys
import numba

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


@numba.njit
def main(N):
    x = 0
    for a in range(1, N + 1):
        for b in range(1, N // a + 1):
            x += a * b
    return x


N = int(read())
print((main(N)))

import sys
import numba

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


@numba.njit("(i8,)", cache=True)
def main(N):
    x = 0
    for a in range(1, N + 1):
        for b in range(1, N // a + 1):
            x += a * b
    return x


N = int(read())
print((main(N)))

-@numba.njit +@numba.njit("(i8,)", cache=True)