## https://yukicoder.me/problems/no/1514

import math

def main():
    N = int(input())

    finished = [False] * (N + 1)
    sqrt_n = int(math.sqrt(N))

    y_map = {}
    for l in reversed(range(1, sqrt_n + 1)):
        
        p = l ** 2
        x = p
        while x <= N:
            if not finished[x]:
                y = x // p
                if y not in y_map:
                    y_map[y] = 0
                y_map[y] += 1
                finished[x] = True
            x += p

    
    for j in range(1, N + 1):
        if not finished[j]:
            if j not in y_map:
                y_map[j] = 0
            y_map[j] += 1
    answer = 0
    for value in y_map.values():
        answer += value ** 2
    print(answer)





                





    
        















if __name__ == "__main__":
    main()