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



read = sys.stdin.buffer.read

readline = sys.stdin.buffer.readline

readlines = sys.stdin.buffer.readlines



def main(N):

    x = 0

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

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

            x += b

    return x



if sys.argv[-1] == 'ONLINE_JUDGE':

    import numba

    from numba.pycc import CC

    i8 = numba.int64

    cc = CC('my_module')



    def cc_export(f, signature):

        cc.export(f.__name__, signature)(f)

        return numba.njit(f)



    main = cc_export(main, (i8, ))

    cc.compile()



from my_module import main



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

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


def main(N):
    x = 0
    for a in range(1, N + 1):
        for b in range(a, N + 1, a):
            x += b
    return x


if sys.argv[-1] == "ONLINE_JUDGE":
    import numba
    from numba.pycc import CC

    i8 = numba.int64
    cc = CC("my_module")

    def cc_export(f, signature):
        cc.export(f.__name__, signature)(f)
        return numba.njit(f)

    main = cc_export(main, (i8,))
    cc.compile()
from my_module import main

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

-import numba -@numba.njit("(i8,)", cache=True) -        for b in range(1, N // a + 1): -            x += a * b +        for b in range(a, N + 1, a): +            x += b +if sys.argv[-1] == "ONLINE_JUDGE": +    import numba +    from numba.pycc import CC + +    i8 = numba.int64 +    cc = CC("my_module") + +    def cc_export(f, signature): +        cc.export(f.__name__, signature)(f) +        return numba.njit(f) + +    main = cc_export(main, (i8,)) +    cc.compile() +from my_module import main +