def cal_prime(n):
    prime = [1] * (n + 1)
    prime[0] = prime[1] = 0
    for i in range(2, n + 1):
        j = i * i
        while j <= n:
            prime[j] = 0
            j += i

    res = []
    for idx, num in enumerate(prime):
        if num:
            res.append(idx)

    return res