对每个数字分解素因子，最后对每个素因子去其最大的指数，然后把不同素因子的最大指数次幂相乘，得到的就是最小公倍数

python不熟练，代码比较挫

mp = {}def process(n):    i = 2    while i*i <= n:        cnt = 0        if n%i == 0:            while n%i == 0:                cnt += 1                n /= i            if i in mp:                mp[i] = max(mp[i], cnt)            else:                mp[i] = cnt        i += 1    if n > 1:        if n in mp:            mp[n] = max(mp[n], 1)        else:            mp[n] = 1for i in range(2,21):    process(i)res = 1for x in mp:    res *= (x**mp[x])print res