#!/usr/bin/env python3

from lib import primegen
from math import log

def maxpw(n, logN):
    return int(logN / log(n))

def M(p, q, logN):
    return max(q**pw * p**maxpw(p, logN - pw*log(q))
               for pw in range(1, maxpw(q, logN - log(p))+1)
              )

N = 10**7
logN = log(N)

primes = list(primegen(N//2+1))

s = 0

for i, p in enumerate(primes):
    if p > int(N**0.5):
        break
    for q in primes[i+1:]:
        if p*q > N:
            break
        s += M(p, q, logN)

print(s)