Buggy python submission (verdict: Runtime Error):
import sys
sys.setrecursionlimit(10**6)
from math import floor,ceil,sqrt,factorial,log,gcd
from heapq import heappop, heappush, heappushpop
from collections import Counter,defaultdict,deque
from itertools import accumulate,permutations,combinations,product,combinations_with_replacement
from bisect import bisect_left,bisect_right
from copy import deepcopy
from operator import itemgetter
from fractions import gcd
mod = 10 ** 9 + 7
inf = float('inf')
ninf = -float('inf')

#Pythonを用いる場合
#numpy 1.18.0, scipy 1.4.1, scikit-learn 0.22, numba 0.47.0, networkx 2.4
 
import numpy as np
from scipy.sparse.csgraph import shortest_path, floyd_warshall, dijkstra, bellman_ford, johnson
from scipy.sparse import csr_matrix

 
#整数input
def ii(): return int(sys.stdin.readline().rstrip()) #int(input())
def mii(): return map(int,sys.stdin.readline().rstrip().split())
def limii(): return list(mii()) #list(map(int,input().split()))
def lin(n:int): return [ii() for _ in range(n)]
def llint(n: int): return [limii() for _ in range(n)]
#文字列input
def ss(): return sys.stdin.readline().rstrip() #input()
def mss(): return sys.stdin.readline().rstrip().split()
def limss(): return list(mss()) #list(input().split())
def lst(n:int): return [ss() for _ in range(n)]
def llstr(n: int): return [limss() for _ in range(n)]

#本当に貪欲法か？ DP法では？？
#本当に貪欲法か？ DP法では？？
#本当に貪欲法か？ DP法では？？

n=ii()

ans=0

for i in range(1,n+1):
    
    q=(n//i)*(2*i+i*(n//i -1))//2
    ans+=q
print(ans)



Fixed submission:
import sys
sys.setrecursionlimit(10**6)
from math import floor,ceil,sqrt,factorial,log
from heapq import heappop, heappush, heappushpop
from collections import Counter,defaultdict,deque
from itertools import accumulate,permutations,combinations,product,combinations_with_replacement
from bisect import bisect_left,bisect_right
from copy import deepcopy
from operator import itemgetter
from fractions import gcd
mod = 10 ** 9 + 7
inf = float('inf')
ninf = -float('inf')

#Pythonを用いる場合
#numpy 1.18.0, scipy 1.4.1, scikit-learn 0.22, numba 0.47.0, networkx 2.4

#import numpy as np
#from scipy.sparse.csgraph import shortest_path, floyd_warshall, dijkstra, bellman_ford, johnson
#from scipy.sparse import csr_matrix

 
#整数input
def ii(): return int(sys.stdin.readline().rstrip()) #int(input())
def mii(): return map(int,sys.stdin.readline().rstrip().split())
def limii(): return list(mii()) #list(map(int,input().split()))
def lin(n:int): return [ii() for _ in range(n)]
def llint(n: int): return [limii() for _ in range(n)]
#文字列input
def ss(): return sys.stdin.readline().rstrip() #input()
def mss(): return sys.stdin.readline().rstrip().split()
def limss(): return list(mss()) #list(input().split())
def lst(n:int): return [ss() for _ in range(n)]
def llstr(n: int): return [limss() for _ in range(n)]

#本当に貪欲法か？ DP法では？？
#本当に貪欲法か？ DP法では？？
#本当に貪欲法か？ DP法では？？

n=ii()

ans=0

for i in range(1,n+1):
    
    q=(n//i)*(2*i+i*(n//i -1))//2
    ans+=q
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(10**6)
from math import floor,ceil,sqrt,factorial,log,gcd
from heapq import heappop, heappush, heappushpop
from collections import Counter,defaultdict,deque
from itertools import accumulate,permutations,combinations,product,combinations_with_replacement
from bisect import bisect_left,bisect_right
from copy import deepcopy
from operator import itemgetter
from fractions import gcd
mod = 10 ** 9 + 7
inf = float('inf')
ninf = -float('inf')

#Pythonを用いる場合
#numpy 1.18.0, scipy 1.4.1, scikit-learn 0.22, numba 0.47.0, networkx 2.4
 
import numpy as np
from scipy.sparse.csgraph import shortest_path, floyd_warshall, dijkstra, bellman_ford, johnson
from scipy.sparse import csr_matrix

 
#整数input
def ii(): return int(sys.stdin.readline().rstrip()) #int(input())
def mii(): return map(int,sys.stdin.readline().rstrip().split())
def limii(): return list(mii()) #list(map(int,input().split()))
def lin(n:int): return [ii() for _ in range(n)]
def llint(n: int): return [limii() for _ in range(n)]
#文字列input
def ss(): return sys.stdin.readline().rstrip() #input()
def mss(): return sys.stdin.readline().rstrip().split()
def limss(): return list(mss()) #list(input().split())
def lst(n:int): return [ss() for _ in range(n)]
def llstr(n: int): return [limss() for _ in range(n)]

#本当に貪欲法か？ DP法では？？
#本当に貪欲法か？ DP法では？？
#本当に貪欲法か？ DP法では？？

n=ii()

ans=0

for i in range(1,n+1):
    
    q=(n//i)*(2*i+i*(n//i -1))//2
    ans+=q
print(ans)



Fixed submission:
import sys
sys.setrecursionlimit(10**6)
from math import floor,ceil,sqrt,factorial,log
from heapq import heappop, heappush, heappushpop
from collections import Counter,defaultdict,deque
from itertools import accumulate,permutations,combinations,product,combinations_with_replacement
from bisect import bisect_left,bisect_right
from copy import deepcopy
from operator import itemgetter
from fractions import gcd
mod = 10 ** 9 + 7
inf = float('inf')
ninf = -float('inf')

#Pythonを用いる場合
#numpy 1.18.0, scipy 1.4.1, scikit-learn 0.22, numba 0.47.0, networkx 2.4

#import numpy as np
#from scipy.sparse.csgraph import shortest_path, floyd_warshall, dijkstra, bellman_ford, johnson
#from scipy.sparse import csr_matrix

 
#整数input
def ii(): return int(sys.stdin.readline().rstrip()) #int(input())
def mii(): return map(int,sys.stdin.readline().rstrip().split())
def limii(): return list(mii()) #list(map(int,input().split()))
def lin(n:int): return [ii() for _ in range(n)]
def llint(n: int): return [limii() for _ in range(n)]
#文字列input
def ss(): return sys.stdin.readline().rstrip() #input()
def mss(): return sys.stdin.readline().rstrip().split()
def limss(): return list(mss()) #list(input().split())
def lst(n:int): return [ss() for _ in range(n)]
def llstr(n: int): return [limss() for _ in range(n)]

#本当に貪欲法か？ DP法では？？
#本当に貪欲法か？ DP法では？？
#本当に貪欲法か？ DP法では？？

n=ii()

ans=0

for i in range(1,n+1):
    
    q=(n//i)*(2*i+i*(n//i -1))//2
    ans+=q
print(ans)