import numpy as np

from numba import jit





@jit

def main(n):

    dp = np.zeros(n+1,np.int64)

    #dp[1]=1

    for i in range(1,n+1):

        for j in range(i,n+1,i):

            dp[j]+=1

    dp*=np.arange(n+1)

    return dp.sum()



n = int(eval(input()))

print((main(n)))
import numpy as np



def solve(stdin):

    n = stdin[0]

    dp = np.zeros(n+1,dtype=np.int64)

    for i in range(1,n+1):

        for j in range(i,n+1,i):

            dp[j]+=1

    dp*=np.arange(n+1)

    return dp.sum()



def main():

    stdin = np.fromstring(open(0).read(), dtype=np.int64, sep=' ')

    print((solve(stdin)))



def cc_export():

    from numba.pycc import CC

    cc = CC('my_module')

    cc.export('solve', '(i8[:],)')(solve)

    cc.compile()



if __name__ == '__main__':

    import sys

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

        cc_export()

        exit(0)

    from my_module import solve

    main()
import numpy as np
from numba import jit


@jit
def main(n):
    dp = np.zeros(n + 1, np.int64)
    # dp[1]=1
    for i in range(1, n + 1):
        for j in range(i, n + 1, i):
            dp[j] += 1
    dp *= np.arange(n + 1)
    return dp.sum()


n = int(eval(input()))
print((main(n)))

import numpy as np


def solve(stdin):
    n = stdin[0]
    dp = np.zeros(n + 1, dtype=np.int64)
    for i in range(1, n + 1):
        for j in range(i, n + 1, i):
            dp[j] += 1
    dp *= np.arange(n + 1)
    return dp.sum()


def main():
    stdin = np.fromstring(open(0).read(), dtype=np.int64, sep=" ")
    print((solve(stdin)))


def cc_export():
    from numba.pycc import CC

    cc = CC("my_module")
    cc.export("solve", "(i8[:],)")(solve)
    cc.compile()


if __name__ == "__main__":
    import sys

    if sys.argv[-1] == "ONLINE_JUDGE":
        cc_export()
        exit(0)
    from my_module import solve

    main()

-from numba import jit -@jit -def main(n): -    dp = np.zeros(n + 1, np.int64) -    # dp[1]=1 +def solve(stdin): +    n = stdin[0] +    dp = np.zeros(n + 1, dtype=np.int64) -n = int(eval(input())) -print((main(n))) +def main(): +    stdin = np.fromstring(open(0).read(), dtype=np.int64, sep=" ") +    print((solve(stdin))) + + +def cc_export(): +    from numba.pycc import CC + +    cc = CC("my_module") +    cc.export("solve", "(i8[:],)")(solve) +    cc.compile() + + +if __name__ == "__main__": +    import sys + +    if sys.argv[-1] == "ONLINE_JUDGE": +        cc_export() +        exit(0) +    from my_module import solve + +    main()